全文获取类型
收费全文 | 408097篇 |
免费 | 26630篇 |
国内免费 | 4106篇 |
专业分类
耳鼻咽喉 | 5538篇 |
儿科学 | 8709篇 |
妇产科学 | 10598篇 |
基础医学 | 56623篇 |
口腔科学 | 12263篇 |
临床医学 | 33277篇 |
内科学 | 83092篇 |
皮肤病学 | 9191篇 |
神经病学 | 29126篇 |
特种医学 | 14876篇 |
外国民族医学 | 95篇 |
外科学 | 64261篇 |
综合类 | 13585篇 |
现状与发展 | 5篇 |
一般理论 | 83篇 |
预防医学 | 19212篇 |
眼科学 | 10500篇 |
药学 | 33375篇 |
20篇 | |
中国医学 | 3249篇 |
肿瘤学 | 31155篇 |
出版年
2021年 | 3941篇 |
2020年 | 2616篇 |
2019年 | 3631篇 |
2018年 | 5515篇 |
2017年 | 4323篇 |
2016年 | 4412篇 |
2015年 | 5174篇 |
2014年 | 7137篇 |
2013年 | 8781篇 |
2012年 | 12157篇 |
2011年 | 12382篇 |
2010年 | 7438篇 |
2009年 | 6873篇 |
2008年 | 10973篇 |
2007年 | 11805篇 |
2006年 | 11684篇 |
2005年 | 10793篇 |
2004年 | 9862篇 |
2003年 | 9433篇 |
2002年 | 9013篇 |
2001年 | 28880篇 |
2000年 | 29423篇 |
1999年 | 24307篇 |
1998年 | 5533篇 |
1997年 | 4583篇 |
1996年 | 4087篇 |
1995年 | 3743篇 |
1994年 | 3326篇 |
1993年 | 2997篇 |
1992年 | 16318篇 |
1991年 | 15061篇 |
1990年 | 14386篇 |
1989年 | 14171篇 |
1988年 | 12764篇 |
1987年 | 12237篇 |
1986年 | 11254篇 |
1985年 | 10453篇 |
1984年 | 7007篇 |
1983年 | 5660篇 |
1982年 | 2761篇 |
1979年 | 5536篇 |
1978年 | 3391篇 |
1977年 | 3021篇 |
1975年 | 2676篇 |
1974年 | 3120篇 |
1973年 | 2913篇 |
1972年 | 2879篇 |
1971年 | 2800篇 |
1970年 | 2542篇 |
1969年 | 2578篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Smooth muscle relaxant effect of dehydroindicolactone 总被引:1,自引:0,他引:1
Dehydroindicolactone, a novel linear furanocoumarin with an 8-substituted side chain carrying a 5-member ring lactone, showed spasmolytic activity in a number of smooth muscle preparations. The spasmolytic activity seems to lie in its ability to block the dihydropyridine-sensitive calcium channel. 相似文献
995.
V P Addonizio C A Fisher J F Strauss V A Ewan F R Rickles E F Rosato A H Harken W Y Inouye 《Surgery》1987,101(6):753-762
Disseminated intravascular coagulation invariably accompanies placement of peritoneovenous (LeVeen) shunts, which suggests that ascitic fluid contains procoagulant material capable of activating blood coagulation. In this study, we identified thrombogenic activity in human ascites and the hemostatic pathway by which it acts. Peritoneal fluid was removed percutaneously from patients with ascites due to various causes. Four fractions were prepared by centrifugation: cells, a low-speed, cell-free fluid, a high-speed supernatant, and the precipitate from the high-speed centrifugation. Cellular fractions from all ascitic fluids shortened a one-stage clotting time of normal pooled plasma by 68% in comparison with saline solution and endotoxin controls. Similarly, the cell-free fluids also shortened the clotting time of normal pooled plasma by 41%. The cellular and cell-free fractions shortened the clotting time of factor VIII-deficient plasma but failed to demonstrate procoagulant activity in factor VII-deficient plasma. These fractions had no effect on platelet aggregation or the platelet release reaction. The high-speed precipitate was dissociated by ethylenediaminetetra-acetate (EDTA) into fluid phase and precipitate, both of which demonstrated procoagulant activity. Furthermore, high-speed precipitate contained protein, phospholipid, and sterol in proportions similar to those of plasma membranes and contained membrane-bound vesicles as identified by means of electron microscopy. This material could be rendered inactive by heating to 100 degrees C for 2 minutes or by incubation with phospholipase C for 15 minutes. Finally, the ability of the high-speed precipitate to shorten the clotting time was prevented by preincubation with a monoclonal antibody, which is known to inhibit the procoagulant activity of human tissue factor. We suggest that several entities contribute to the procoagulant properties of human ascites, with procoagulant material deriving at least in part from peritoneal cells. The sedimentable procoagulant factor appears to be associated with cellular membranes or membrane fragments and is thromboplastin-like in its chemical composition, immunoreactivity, and substrate specificity. 相似文献
996.
D L Cohen L B McCullough R W Kessel A Y Apostolides E R Alden K J Heiderich 《Journal of medical education》1987,62(10):789-798
When medical students become involved in patient care, concerns are raised that have ethical and possibly legal implications. In order to determine compliance with the guidelines of the U.S. government and the Joint Committee on Accreditation of Hospitals pertaining to informed consent, the authors conducted a study of hospital administrators, medical school department chairpersons, and medical school deans (with response rates ranging from 82.3 to 95.1 percent) concerning policies on student involvement in patient care. The results show that only 37.5 percent of all responding teaching hospitals specifically informed patients that students would be involved in care. Only 51 percent of the responding medical schools that specifically gave their students instruction or guidance on initial patient interaction as a matter of policy insisted that their students introduce themselves as students and clarify their role in patient care. The authors conclude that medical educators' compliance with the ethical requirements of informed consent is incomplete. 相似文献
997.
A Menget A Burguet C Fromentin Y Bernard N Cardot 《Archives fran?aises de pédiatrie》1989,46(9):701-702
Through the case report of severe digitalis intoxication in a premature born after 27 weeks of gestation with a birthweight of 800 g, the authors show that anti-digoxin antibodies constitute a very efficacious therapeutic tool which, up to the present, has not been used in prematures. 相似文献
998.
The hepatitis B immunization programme in Singapore 总被引:2,自引:0,他引:2
K T Goh S Doraisingham K L Tan C J Oon M L Ho A J Chen S H Chan 《Bulletin of the World Health Organization》1989,67(1):65-70
A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated. 相似文献
999.
Pinhole collimator scintigraphy in differential diagnosis of metastasis, fracture, and infections of the spine 总被引:1,自引:0,他引:1
The informational gains obtained by the use of pinhole collimator scintigraphy (PCS) have been well documented. The present study has been undertaken to prospectively investigate its efficacy in diagnosing several commonly occurring spinal diseases. Patient material consisted of metastatic cancer (39 vertebrae), compression fractures (33 vertebrae), tuberculous spondylitis (17 vertebrae), and pyogenic spondylitis (six vertebrae). PCS findings were characterized in terms of localization, appearance, and homogeneity of abnormal radionuclide accumulation. Thus, metastatic cancer manifested as diffusely or focally homogeneous accumulation within the vertebral body or as a typical short-segmental accumulation along the end-plate, whereas compression fracture manifested as characteristic board-like accumulation along the entire length of end-plates. Tuberculous spondylitis, on the other hand, revealed homogeneous accumulation throughout the vertebral body, and pyogenic spondylitis revealed accumulation at the end-zone of opposing vertebral bodies giving sandwich-like appearance. The disk space at the affected level was not narrowed in the former two diseases but it was narrowed in the latter two. It was concluded that PCS may be useful in differentiating metastatic cancer, compression fracture, tuberculous spondylitis, and pyogenic spondylitis. 相似文献
1000.