全文获取类型
收费全文 | 899788篇 |
免费 | 62475篇 |
国内免费 | 2334篇 |
专业分类
耳鼻咽喉 | 12475篇 |
儿科学 | 28693篇 |
妇产科学 | 26144篇 |
基础医学 | 126621篇 |
口腔科学 | 24688篇 |
临床医学 | 74825篇 |
内科学 | 183188篇 |
皮肤病学 | 18985篇 |
神经病学 | 71393篇 |
特种医学 | 36448篇 |
外国民族医学 | 336篇 |
外科学 | 142133篇 |
综合类 | 19031篇 |
一般理论 | 247篇 |
预防医学 | 64590篇 |
眼科学 | 20085篇 |
药学 | 63808篇 |
中国医学 | 1799篇 |
肿瘤学 | 49108篇 |
出版年
2018年 | 9050篇 |
2017年 | 7160篇 |
2016年 | 7678篇 |
2015年 | 8730篇 |
2014年 | 12375篇 |
2013年 | 19216篇 |
2012年 | 25662篇 |
2011年 | 27275篇 |
2010年 | 16583篇 |
2009年 | 15789篇 |
2008年 | 26146篇 |
2007年 | 27747篇 |
2006年 | 27929篇 |
2005年 | 27469篇 |
2004年 | 26308篇 |
2003年 | 25476篇 |
2002年 | 25064篇 |
2001年 | 41359篇 |
2000年 | 42557篇 |
1999年 | 36273篇 |
1998年 | 9973篇 |
1997年 | 9151篇 |
1996年 | 9088篇 |
1995年 | 8446篇 |
1994年 | 8081篇 |
1993年 | 7584篇 |
1992年 | 28199篇 |
1991年 | 26979篇 |
1990年 | 26408篇 |
1989年 | 25348篇 |
1988年 | 23555篇 |
1987年 | 23171篇 |
1986年 | 22252篇 |
1985年 | 21154篇 |
1984年 | 15808篇 |
1983年 | 13478篇 |
1982年 | 8087篇 |
1979年 | 14592篇 |
1978年 | 10208篇 |
1977年 | 8627篇 |
1976年 | 8148篇 |
1975年 | 8959篇 |
1974年 | 10697篇 |
1973年 | 10182篇 |
1972年 | 9661篇 |
1971年 | 8917篇 |
1970年 | 8584篇 |
1969年 | 8025篇 |
1968年 | 7684篇 |
1967年 | 7086篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
141.
S G Thompson G Calori J M Thomson F Haverkate F Duckert 《Thrombosis and haemostasis》1991,65(2):149-152
As an adjunct to a European multicentre prospective study, five quality assessment (QA) exercises, spanning a period of 2.5 years, were undertaken. In these, fifteen laboratories from eight countries each performed ten haemostatic factor assays. The design of the QA exercises allowed the between-duplicate, between-day and between-laboratory coefficients of variation (CVs) to be calculated. The between-duplicate CV decreased by a factor of one quarter, and the between-day CV by a factor of one third, over the five exercises. The activated partial thromboplastin time (APTT) assay consistently showed the lowest CVs, while there was notable improvement in the between-day CVs for von Willebrand factor related antigen (vWF R:Ag) and factor VIII clotting activity (VIII:C). However, the between-laboratory CV, assessing extent of agreement between the different laboratories, did not apparently improve over the five exercises. Thus, while QA exercises may be very useful in improving the performance of haemostatic assays according to criteria which an individual laboratory can assess, improving agreement on haemostatic assay results between laboratories may be more difficult to achieve. 相似文献
142.
Three cases of cervical epidural hematoma are reported. Acute neck pain usually associated with a mild effort, closely followed by radicular pain and a neurologic deficit below the lesion is the typical presentation of this extremely rare and difficult diagnosis. As prognosis depends on preoperative neurologic state, the authors emphasize the importance of prompt identification of this lesion. The diagnosis is confirmed by computed tomography, and emergency neurosurgical laminectomy is mandatory. 相似文献
143.
Double-blind, placebo-controlled comparison of clonazepam and alprazolam for panic disorder 总被引:1,自引:0,他引:1
G E Tesar J F Rosenbaum M H Pollack M W Otto G S Sachs J B Herman L S Cohen S A Spier 《The Journal of clinical psychiatry》1991,52(2):69-76
To test the reported antipanic efficacy of clonazepam, the authors randomized 72 subjects with panic disorder to 6 weeks of treatment with either alprazolam, clonazepam, or placebo. Endpoint analysis demonstrated a significant beneficial effect of both active treatments, but not placebo treatment, on the frequency of panic attacks, overall phobia ratings, and the extent of disability. Comparison of the two active treatments revealed no significant differences and no consistent tendency for one agent to be favored over another, although power to detect small differences was limited. Sedation and ataxia were the most common side effects reported, but these effects were mild and transient and did not interfere with treatment outcome. The results of this double-blind, placebo-controlled trial are consistent with previous reports of clonazepam's antipanic efficacy. 相似文献
144.
C Caron J Goudemand A Marey D Beague G Ducroux F Drouvin 《Thrombosis and haemostasis》1991,66(4):410-414
The plasma levels of several haemostatic and fibrinolytic parameters were measured before and after delivery in 61 hypertensive pregnant women of whom 22 developed preeclampsia, and compared to the results obtained in 42 normal pregnant women. In the two last weeks before delivery (D less than or equal to -15) tPA antigen, PAI-1 activity, vWF:Ag/FVIII:C ratio, ATIII activity and platelet count were found to be significantly different in the hypertensive pregnant women with and without preeclampsia. Combined all together, an association of three of these five parameters were found to be pathological (i.e.:tPA:Ag greater than or equal to 19 ng/ml, PAI-1 activity greater than or equal to 58 IU/ml, vWF:Ag/FVIII:C ratio greater than or equal to 2.6, ATIII activity less than or equal to 73%) in none of the hypertensive women without preeclampsia and in only 35% of the preeclamptic group. A positive correlation was demonstrated between vWF:Ag/FVIII:C ratio and tPA:antigen levels suggesting that both tPA and vWF:Ag could be considered as early indicators of a possible micro angiopathy occurring in preeclampsia. However, due to the high dispersion of the results, it appears that the investigated haemostatic and/or fibrinolytic criteria give only presumptive arguments before assigning risk for preeclampsia development among hypertensive pregnant women. 相似文献
145.
146.
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors. 相似文献
147.
In a previous study, we described a new method [3] to measure Na reabsorption by each segment of the human nephron independently. Reabsorption was expressed as equivalent volumes of solute-free water (CH2O) generated by the loop of Henle (CH2O-HL) and by the distal tubule (CH2O-DT), and dissipated by back diffusion (BD) across collecting ducts (CH2O-BD). These data were obtained during maximal water diuresis (MWD). The present study was undertaken to calculate CH2O-HL by experiments performed during maximal antidiuresis (MA). For this purpose, a new theoretical approach was devised, described by algebraic equations which allowed calculations of segmental transport during MA alone, where only CH2O-HL could be calculated independently. The study was performed on 14 normal volunteers who were studied twice by clearance measurements, firstly during MWD and again during MA. In each experiment, clearance periods were performed during baseline conditions and during the administration of furosemide (0.7 mg/kg bolus injection followed by 0.06 mg/kg/min maintenance infusion). From the values measured during either condition, segmental reabsorption was calculated. During MWD, CH2O-HL averaged 19.4 + 10.4, during MA 20.4 + 8.0 ml/min/GFR X 100; p greater than 0.05. The paired measurements were significantly correlated (r = 0.80; p less than 0.01). These data demonstrate that CH2O-HL obtained with the original theory is a reproducible result that can be confirmed with independent measurements obtained during different experimental conditions. Thus, measurements of segmental Na transport in the human nephron are feasible and can contribute important informations on disease states. 相似文献
148.
F Brown 《British medical journal》1987,295(6594):347-348
149.
Authors with wide experience report that the Shouldice technique for repair of inguinal hernia is very effective. The technique has not gained widespread acceptance or notoriety. For example, the 13th edition of Textbook of Surgery, edited by Sabiston, devotes only one paragraph to this type of herniorrhaphy. Because of the excellent results reported by the Shouldice Clinic, this technique was adopted at the Augusta Veterans Administration Hospital, a teaching hospital of the Medical College of Georgia. Since 1976, a total of 604 Shouldice repairs have been performed by supervised house staff; 468 patients have been followed for up to 8 years and a recurrence rate of 1.3 per cent is reported. Although the follow-up is brief, the Shouldice hernia repair is widely applicable and good results are not dependent on wide experience alone. 相似文献
150.