全文获取类型
收费全文 | 5419篇 |
免费 | 276篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 91篇 |
妇产科学 | 117篇 |
基础医学 | 681篇 |
口腔科学 | 56篇 |
临床医学 | 541篇 |
内科学 | 1017篇 |
皮肤病学 | 57篇 |
神经病学 | 680篇 |
特种医学 | 161篇 |
外科学 | 924篇 |
综合类 | 62篇 |
一般理论 | 5篇 |
预防医学 | 308篇 |
眼科学 | 353篇 |
药学 | 301篇 |
中国医学 | 2篇 |
肿瘤学 | 257篇 |
出版年
2022年 | 33篇 |
2021年 | 68篇 |
2020年 | 46篇 |
2019年 | 61篇 |
2018年 | 95篇 |
2017年 | 89篇 |
2016年 | 87篇 |
2015年 | 87篇 |
2014年 | 132篇 |
2013年 | 223篇 |
2012年 | 272篇 |
2011年 | 298篇 |
2010年 | 160篇 |
2009年 | 158篇 |
2008年 | 245篇 |
2007年 | 273篇 |
2006年 | 266篇 |
2005年 | 245篇 |
2004年 | 216篇 |
2003年 | 237篇 |
2002年 | 224篇 |
2001年 | 145篇 |
2000年 | 162篇 |
1999年 | 126篇 |
1998年 | 57篇 |
1997年 | 63篇 |
1996年 | 40篇 |
1995年 | 49篇 |
1994年 | 51篇 |
1993年 | 35篇 |
1992年 | 99篇 |
1991年 | 81篇 |
1990年 | 77篇 |
1989年 | 67篇 |
1988年 | 68篇 |
1987年 | 66篇 |
1986年 | 81篇 |
1985年 | 76篇 |
1984年 | 61篇 |
1983年 | 60篇 |
1982年 | 37篇 |
1981年 | 32篇 |
1980年 | 34篇 |
1979年 | 58篇 |
1978年 | 33篇 |
1977年 | 23篇 |
1975年 | 29篇 |
1974年 | 34篇 |
1973年 | 36篇 |
1933年 | 26篇 |
排序方式: 共有5705条查询结果,搜索用时 15 毫秒
61.
Post M 《Seminars in Arthroplasty》1990,1(2):151-159
Constrained arthroplasty is occasionally needed to salvage a destroyed glenohumeral joint when the rotator cuff is nonfunctioning and when an unconstrained prosthesis will not suffice. There is a high failure rate because of the severe forces between such a device and the contiguous bone. Accordingly, it is essential to know the limitations of constrained arthroplasty and when it should be avoided. For example, when the bone of the glenoid vault is highly demineralized or deficient or if there is a history of seizure disorder or alcoholism, use of such a device is contraindicated. Postoperatively, excessive force and extremes of motion should also be avoided during the rehabilitation program to avoid bone fracture or dislocation of the prosthesis. Various complications have been observed with constrained arthroplasty, including dislocation, bone fracture, pullout of the glenoid, infection, radial nerve injury after extrusion of bone cement through the humeral cortex when the cement has been pressurized, and screw breakage in a relative small number of cases after metal fatigue and loosening of the glenoid component. When the glenoid component has pulled away from the glenoid vault, it may be necessary to remove this component; the humeral head may be fitted with a bipolar 40- to 44-mm acetabular component, thereby allowing at least preservation, if not the active function of the shoulder contour. 相似文献
62.
63.
Aanesen Arthur; Fried Gabriel; Andersson Eva; Gottlieb Claes 《Human reproduction (Oxford, England)》1995,10(7):1885-1890
The possible presence of -aminobutyric acid (GABA) specificbinding sites on human spermatozoa was investigated. Swim-uppreparations of human spermatozoa were incubated with radiolabelledGABA in the presence of unlabelled GABA, alternatively displacersof GABAA/B receptors and GABA transport proteins. The resultsindicate that GABA specific binding sites are present on thesurface of human spermatozoa, and that these binding sites possiblyindicate the presence of GABA transport proteins. Furthermore,GABA at different concentrations was added to swim-up preparationsof human spermatozoa. Possible effects of GABA on sperm motility,hyperactivation and acrosome reaction were explored. No significantdifferences were observed between treated groups and controlsconcerning motility parameters and hyperactivation. Incubationwith GABA did not cause any increase in spontaneous acrosomereaction. However, spermatozoa treated with the calcium ionophoreA-23187 showed a small but significantly increased ability toundergo the acrosome reaction following preincubation in 104M GABA (P < 0.05). 相似文献
64.
Claes LE Wilke HJ Augat P Rübenacker S Margevicius KJ 《Clinical biomechanics (Bristol, Avon)》1995,10(5):227-234
We asked whether dynamization of externally fixed diaphyseal fractures could improve bone healing in comparison to rigid fixation of fractures having similar remaining gap sizes. To answer this question we evaluated metatarsal osteotomies in 12 sheep. The osteotomy with a 0.6-mm gap was stabilized with a specially designed high bending and torsional stiffness external ring fixator. Osteotomies in six sheep were stabilized rigidly (axial movement < 0.06 mm) or dynamically (axial movement 0.15-0.34 mm). The cyclical axial interfragmentary movement was caused by the load-bearing of the operated limb. With increasing healing time, the initially allowed movement was decreased by callus formation around the osteotomy. The reduction in interfragmentary movement was measured and monitored by a linear variable displacement transducer at the external fixator and a telemetry system. After 9 weeks the sheep were sacrificed and the healed bones were investigated biomechanically and histomorphologically. Compared to the rigidly fixed osteotomies, the dynamized osteotomies showed significantly (P < 0.05) greater (+41%) callus formation and 45% greater tensile strength of the newly formed bone in the cortical osteotomy gap. Histological analysis indicated that the effect of dynamization occurred mainly after the 5th week. RELEVANCE: From these results we conclude that dynamic fixation of diaphyseal gaps is advantageous in comparison to stable external fixation. 相似文献
65.
Gabapentin in the acute treatment of refractory bipolar disorder 总被引:4,自引:0,他引:4
Altshuler LL Keck PE McElroy SL Suppes T Brown ES Denicoff K Frye M Gitlin M Hwang S Goodman R Leverich G Nolen W Kupka R Post R 《Bipolar disorders》1999,1(1):61-65
Background: Gabapentin, a new anti-epileptic agent, has been anecdotally reported to be effective in the treatment of mania. We systematically assessed the response rate in bipolar patients being treated adjunctively with gabapentin for manic symptoms, depressive symptoms, or rapid cycling not responsive to standard treatments.
Method: Twenty-eight bipolar patients experiencing manic (n=18), depressive (n=5), or rapid-cycling (n=5) symptoms inadequately responsive to at least one mood stabilizer were treated in an open fashion with adjunctive gabapentin. Illness response was assessed using the Clinical Global Impression Scale modified for bipolar disorder (CGI-BP). A 'positive response' was operationalized as a CGI response of much or very much improved.
Results: Fourteen of the 18 (78%) treated for hypomania or mania had a positive response to a dosage range of 600–3600 mg/day. Patients with hypomania responded fastest, with a positive response achieved in 12.7±7.2 days. Patients with classic mania had a mean time to positive response of 25±12 days, and in patients with mixed mania it was 31.8±20.9 days. All of the five patients treated for depression had a positive response within 21±13.9 days. Only one of five patients with rapid cycling had a positive response. Gabapentin was well tolerated by all patients, with the most common side-effect being sedation.
Conclusions: Gabapentin appears to have acute anti-manic and anti-depressant properties as an adjunctive agent for refractory bipolar illness. Prospective double-blind studies are needed to further delineate its acute efficacy when used as monotherapy and its prophylactic efficacy as monotherapy or in conjuction with other mood stabilizers. 相似文献
Method: Twenty-eight bipolar patients experiencing manic (n=18), depressive (n=5), or rapid-cycling (n=5) symptoms inadequately responsive to at least one mood stabilizer were treated in an open fashion with adjunctive gabapentin. Illness response was assessed using the Clinical Global Impression Scale modified for bipolar disorder (CGI-BP). A 'positive response' was operationalized as a CGI response of much or very much improved.
Results: Fourteen of the 18 (78%) treated for hypomania or mania had a positive response to a dosage range of 600–3600 mg/day. Patients with hypomania responded fastest, with a positive response achieved in 12.7±7.2 days. Patients with classic mania had a mean time to positive response of 25±12 days, and in patients with mixed mania it was 31.8±20.9 days. All of the five patients treated for depression had a positive response within 21±13.9 days. Only one of five patients with rapid cycling had a positive response. Gabapentin was well tolerated by all patients, with the most common side-effect being sedation.
Conclusions: Gabapentin appears to have acute anti-manic and anti-depressant properties as an adjunctive agent for refractory bipolar illness. Prospective double-blind studies are needed to further delineate its acute efficacy when used as monotherapy and its prophylactic efficacy as monotherapy or in conjuction with other mood stabilizers. 相似文献
66.
Lack of commercially available antidotes for animals is an issue of significant concern to the American Board of Veterinary Toxicology. A few antidotes are available for food animals through extra-label use, regulatory discretion and compounding. However, regulatory restrictions arising from human food, safety concerns have limited the availability of food animal antidotes. Use of some antidotes in food animals requires establishment of an investigational new animal drug application. Antidotes are generally more available for non-food animals from several sources: approved animal drugs, extra-label use of approved animal and human drugs, regulatory discretion and compounding. Present alternatives are discussed as well as the need for legislation to increase antidote availability. Human food safety will always be an issue for food animal antidotes. Future availability of non-food animal and food animal antidotes will depend on several mechanisms and may include the establishment of veterinary antidote depots. Stakeholders are encouraged to participate in identifying and implementing these mechanisms. 相似文献
67.
Urken ML Catalano PJ Sen C Post K Futran N Biller HF 《Archives of otolaryngology--head & neck surgery》1993,119(12):1318-1325
OBJECTIVE: The role of free flaps in skull base reconstruction is discussed in detail. Twenty-six microvascular free tissue transfers performed in 22 patients are reviewed in detail. A classification scheme for skull base defects is presented. SETTING: Tertiary referral center. PATIENTS: Twenty-two patients with neoplasms that involve the skull base underwent a combined craniotomy and facial approach for resection. The resultant defects were reconstructed with a variety of microvascular free flaps. RESULTS: All 22 patients were ultimately successfully reconstructed with a free flap. One patient required a second free flap following ablative surgery for a recurrent tumor. The initial free flaps in three patients were unsuccessful and a second flap was required. The classification scheme was applied to all defects. CONCLUSIONS: The creation of a functional separation of the intracranial and extracranial cavities can be extremely difficult to accomplish, especially when multiple cavities (nasal, oral, pharyngeal) are violated. Free flaps provide a solution to this problem in select cases. Skull base defects can and should be classified for the purpose of communication, treatment planning, prognosis of reconstruction, and judging therapeutic outcome. 相似文献
68.
R W Cowdry M H Ebert D P van Kammen R M Post F K Goodwin 《Neuropsychopharmacology》1983,18(11):1287-1299
Probenecid is used to block the transport of acid monoamine metabolites from cerebrospinal fluid (CSF), on the assumption that the resultant rise in CSF concentrations of the metabolites will reflect presynaptic "turnover" of the parent monoamine. However, CSF levels of probenecid correlate with CSF levels of the metabolite, suggesting that the blockade is incomplete at the probenecid levels obtained in human studies. This article reviews the literature on CSF probenecid-metabolite correlations and presents data demonstrating variations in the correlations across diagnostic groups. These cross-diagnostic variations may be due to group differences in membrane transport characteristics and and confound attempts to "correct for" CSF probenecid concentrations in studies of monoamine turnover. 相似文献
69.
A Van Schepdael J Delcourt M Mulier R Busson L Verbist H J Vanderhaeghe M P Mingeot-Leclercq P M Tulkens P J Claes 《Journal of medicinal chemistry》1991,34(4):1468-1475
The clinical use of the potent, wide-spectrum aminoglycoside antibiotics is limited by oto- and nephrotoxicities. The latter is related to the binding of these polycationic drugs to negatively charged phospholipids and to the subsequent inhibition of lysosomal phospholipases. In order to explore the influence of a modification of the hydrophobic/hydrophilic balance at a specific site of an aminoglycoside, kanamycin B has been chemically modified in position 6" by substitution of the hydroxyl group with a halogen atom (or a pseudohalogen group), or an amino, an amido, a thioalkyl, or an alkoxy group, each series containing increasingly bulkier chains. Examination of the antibacterial activity of the synthesized compounds revealed a negative correlation between the size of the 6"-substituent and the antibacterial activity against kanamycin B sensitive Gram-positive and -negative organisms. Only derivatives with small substituents in position 6", namely chloro, bromo, azido, amino, methylcarbamido, acetamido, methylthio, methylsulfinyl, O-methyl, O-ethyl, and O-isopropyl, showed acceptable activity (geometric mean of minimum inhibitory concentrations for Gram-negative strains less than or equal to 2.5 mg/L; value for kanamycin B, 0.5 mg/L). In vitro toxicological evaluation of all derivatives and computer-aided conformational analysis of selected compounds inserted in a phosphatidylinositol monolayer are presented in the following paper in this issue. 相似文献
70.
A Van Schepdael R Busson H J Vanderhaeghe P J Claes L Verbist M P Mingeot-Leclercq R Brasseur P M Tulkens 《Journal of medicinal chemistry》1991,34(4):1483-1492
Substitution of the C-1 atom in the 2-deoxystreptamine moiety of gentamicin C2, a broad-spectrum aminoglycoside antibiotic, by an axial hydroxymethyl group has been reported to confer protection against most clinically important bacterial enzymes inactivating aminoglycosides, while simultaneously reducing the nephrotoxic potential of this drug. We report here on a similar modification of kanamycin B. Microbiological evaluation, however, revealed no useful protection, as established by the almost complete lack of activity of 1-C-(hydroxymethyl)kanamycin B against an array of organisms producing defined types of aminoglycoside-inactivating enzymes and against which 1-C-(hydroxymethyl)gentamicin C2 and amikacin (1-N-[(S)-2-hydroxy-4-aminobutyryl]kanamycin A) are active. Moreover, toxicological evaluation, based on the in vitro measurement of the drug inhibitory potential toward lysosomal phospholipases, a predictive test of the intrinsic nephrotoxic potential of aminoglycosides, showed not decreased but rather increased toxicity. Comparative conformational analysis of the interactions of the drug with a phosphatidylinositol monolayer explained the lack of protective effect, since no significant change of the mode of insertion of the derivative in this monolayer was detected compared to that of kanamycin B. Combination of a 1-C-(hydroxymethyl) substituent with a 6"-chloro, 6"-acetamido substituent resulted in a partial improvement of the toxicological behavior with no loss of activity for the 6"-chloro and the 6"-azido derivatives, but not to the extent of obtaining better derivatives than kanamycin B itself. We, therefore, suggest that the advantages of an axial hydroxymethyl substituent at C-1 are probably restricted to the gentamicin family and do not extend to kanamycins. It might be concluded that the structural differences between gentamicins and kanamycins play an important, still undescribed role both in their effective recognition by aminoglycoside-inactivating enzymes, which are responsible for most of the clinically important cases of resistance to aminoglycosides, and also in the interactions with phospholipids, which in turn cause nephrotoxicity. 相似文献