全文获取类型
收费全文 | 28177篇 |
免费 | 1536篇 |
国内免费 | 260篇 |
专业分类
耳鼻咽喉 | 246篇 |
儿科学 | 547篇 |
妇产科学 | 580篇 |
基础医学 | 2869篇 |
口腔科学 | 665篇 |
临床医学 | 2002篇 |
内科学 | 8112篇 |
皮肤病学 | 354篇 |
神经病学 | 2408篇 |
特种医学 | 1068篇 |
外科学 | 5221篇 |
综合类 | 55篇 |
一般理论 | 5篇 |
预防医学 | 1119篇 |
眼科学 | 530篇 |
药学 | 1646篇 |
中国医学 | 57篇 |
肿瘤学 | 2489篇 |
出版年
2024年 | 31篇 |
2023年 | 292篇 |
2022年 | 609篇 |
2021年 | 1035篇 |
2020年 | 591篇 |
2019年 | 839篇 |
2018年 | 1003篇 |
2017年 | 728篇 |
2016年 | 882篇 |
2015年 | 902篇 |
2014年 | 1219篇 |
2013年 | 1505篇 |
2012年 | 2291篇 |
2011年 | 2172篇 |
2010年 | 1255篇 |
2009年 | 1204篇 |
2008年 | 1879篇 |
2007年 | 1823篇 |
2006年 | 1704篇 |
2005年 | 1696篇 |
2004年 | 1600篇 |
2003年 | 1366篇 |
2002年 | 1234篇 |
2001年 | 131篇 |
2000年 | 128篇 |
1999年 | 171篇 |
1998年 | 209篇 |
1997年 | 166篇 |
1996年 | 159篇 |
1995年 | 150篇 |
1994年 | 128篇 |
1993年 | 116篇 |
1992年 | 93篇 |
1991年 | 55篇 |
1990年 | 64篇 |
1989年 | 48篇 |
1988年 | 39篇 |
1987年 | 36篇 |
1986年 | 45篇 |
1985年 | 36篇 |
1984年 | 35篇 |
1983年 | 33篇 |
1982年 | 49篇 |
1981年 | 29篇 |
1980年 | 27篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1976年 | 14篇 |
1975年 | 13篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Duranti R Sanna A Romagnoli I Nerini M Gigliotti F Ambrosino N Scano G 《Pflügers Archiv : European journal of physiology》2004,448(2):222-230
We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P
di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P
abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v
rcm,i) (2.01-fold) and the diaphragm (v
di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P
rcm,i) (1.24-fold) and P
di (0.99-fold) with AG. Instead, with AS, a lower increase in P
abm (2.12-fold), v
rcm,i (1.66-fold) and v
di (1.54-fold) was associated with a greater increase in P
rcm,i (1.56-fold) and P
di (1.97-fold). A combination of P
abm and v
di during AG (Wald 2=23.19, P<0.0000), with the addition of P
rcm,i during AS (Wald 2=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes. 相似文献
103.
Domenico Schiavino Eleonora Nucera Emanuela Pollastrini Tiziana De Pasquale Alessandro Buonomo Francesco Bartolozzi Carla Lombardo Chiara Roncallo Giampiero Patriarca 《Annals of allergy, asthma & immunology》2004,92(4):409-413
BACKGROUND: Hymenoptera venom hypersensitivity is an epidemiologically important problem. The only effective treatment in the management of venom-allergic patients with a history of generalized reactions to insect sting is specific immunotherapy. OBJECTIVE: To demonstrate safety and effectiveness of a modified ultrarush desensitization protocol in venom-allergic patients. METHODS: Fifty-seven patients with Hymenoptera venom allergy underwent a specific 1-day ultrarush desensitization by the subcutaneous route, reaching the cumulative dose of 101.1 microg in 2.5 hours. The maintenance dose (100 microg) was administered after 15 days and thereafter once a month. Patients were followed up for a year. Antihistamines were withheld for 15 days before and during desensitization to not underestimate the incidence of adverse effects. RESULTS: All patients but I completed the ultrarush desensitization. (This patient discontinued the treatment because of a hypertensive crisis not related to the desensitization.) The treatment caused a rapid variation of immunological parameters (IgE, IgG4) since the 15th day. After the desensitization, skin prick test results became negative in 15 patients (27%, decrease of 3.5 log), whereas they decreased in 14 patients (25%, decrease of 1 log). Sixty-four percent showed no adverse effects. Only 7% had a mild systemic reaction. CONCLUSIONS: Ultrarush desensitization is an effective and safe therapy in the management of patients with Hymenoptera venom allergy. In fact, it provides a faster tolerance, without significant differences regarding incidence of severe adverse effects, compared with traditional and rush protocols. It can be adopted for all patients, even children and teenagers. 相似文献
104.
Torti C Quiros-Roldan E Monno L Patroni A Saracino A Angarano G Tinelli C Lo Caputo S Tirelli V Mazzotta F Carosi G;MASTER Cohort GenPheRex Study Group;MASTER Cohort PhenGen Study Group 《Journal of medical virology》2004,74(1):29-33
This study aimed at identifying HIV-1 protease amino acid changes associated with protease inhibitor (PI) exposure and susceptibility. New amino acid substitutions were correlated with the number of experienced PIs, reaching statistical significance only for those at positions 3, 44, and 74. The correspondence multivariate model demonstrated that > or =3 experienced PIs and substitutions or mutations at positions 3, 46, 54, 73, 74, and 84 were correlated with PI cross-resistance, including resistance for lopinavir and amprenavir in this cohort of patients who were naive for these drugs. 相似文献
105.
Zauli D Contestabile S Grassi A Bortolotti R Ballardini G Bianchi FB 《The Journal of allergy and clinical immunology》2002,110(3):538-9; author reply 539
106.
Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean
下载免费PDF全文
![点击此处可从《Journal of anatomy》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Malatesta M Caporaloni C Rossi L Battistelli S Rocchi MB Tonucci F Gazzanelli G 《Journal of anatomy》2002,201(5):409-415
No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is quite poor. Therefore, we investigated the possible effects of a diet containing GM soybean on mouse exocrine pancreas by means of ultrastructural, morphometrical and immunocytochemical analyses. Our observations demonstrate that, although no structural modification occurs in pancreatic acinar cells of mice fed on GM soybean, quantitative changes of some cellular constituents take place in comparison to control animals. In particular, a diet containing significant amount of GM food seems to influence the zymogen synthesis and processing. 相似文献
107.
108.
M. A. De Francesco D. Colombrita G. Pinsi F. Gargiulo S. Caligaris D. Bertelli F. Martinelli J. Gao A. Turano 《European journal of clinical microbiology & infectious diseases》1996,15(7):551-555
One hundred fifty-three blood samples from patients positive for the human immunodeficiency virus (HIV) were analyzed by polymerase chain reaction (PCR) to detect the presence ofMycobacterium avium. Samples were collected from patients who also had blood cultures performed by a radiometric method. Blood samples were centrifuged on a Ficoll-Hypaque gradient to purify peripheral blood mononuclear cells. The purified cells were washed and incubated with a resin, boiled to release mycobacterial DNA, and then amplified. Polymerase chain reaction products were detected by a nonisotopic method. A 123 base-pair (bp) insertion sequence, namely IS6110, fromMycobacterium tuberculosis complex was also included in the reaction as an internal control ofTaq polymerase activity to exclude the presence of enzyme inhibitors. This IS6110 fragment can be distinguished from the 383 bp target product on ethidium bromide-stained agarose gel and may also be used in a colorimetric assay. Such results were compared with the results of culture and indicated that the assay is as sensitive as bacteriological methods, though faster. 相似文献
109.
Calogero Caruso Giuseppina Candore Diego Cigna Gabriele Di Lorenzo Guido Sireci Francesco Dieli Alfredo Salerno 《Immunologic research》1996,15(1):84-90
It is well known that aging is associated with various alterations in lymphoid cell functions, particularly with a progressive decline in immune responsiveness to exogenous antigens and increasing incidence of autoimmune phenomena. Many studies have been focused on the mechanisms of the immunologic features of aging. This review describes our results of studies performed to determine the influence of age on the capacity to produce interleukin-2 (IL-2), interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Mitogen-stimulated cultures of mononuclear cells (MNC) from human beings were assessed for cytokine-producing capacity. A significant decrease in IFN-γ and IL-2 production by MNC cultures from elderly individuals was observed. No significant difference was instead observed between cultures from elderly individuals and those from young ones as regards TNF-α, IL-4 and IL-6 production. Mitogen or antigen-stimulated cultures of MNC from aged mice also displayed a significant decrease in IFN-γ and IL-2 production as well as TNF-β. Instead IL-4 and IL-5 production significantly increased in these cultures. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in the elderly, i.e. a normal or increased humoral response (including autoimmune responses) in face of a low T cell immune responsiveness. 相似文献
110.