首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2404901篇
  免费   179324篇
  国内免费   4119篇
耳鼻咽喉   34532篇
儿科学   72981篇
妇产科学   63050篇
基础医学   336403篇
口腔科学   67775篇
临床医学   216816篇
内科学   471556篇
皮肤病学   48381篇
神经病学   202349篇
特种医学   96559篇
外国民族医学   886篇
外科学   362438篇
综合类   56256篇
现状与发展   1篇
一般理论   978篇
预防医学   191377篇
眼科学   55701篇
药学   178274篇
  56篇
中国医学   4382篇
肿瘤学   127593篇
  2018年   24466篇
  2016年   20965篇
  2015年   23614篇
  2014年   33906篇
  2013年   51332篇
  2012年   69432篇
  2011年   72933篇
  2010年   42940篇
  2009年   41280篇
  2008年   69405篇
  2007年   73759篇
  2006年   74632篇
  2005年   72627篇
  2004年   69874篇
  2003年   67477篇
  2002年   66737篇
  2001年   112532篇
  2000年   116572篇
  1999年   98414篇
  1998年   27928篇
  1997年   25596篇
  1996年   25496篇
  1995年   24648篇
  1994年   23191篇
  1993年   21598篇
  1992年   79398篇
  1991年   76416篇
  1990年   73585篇
  1989年   70857篇
  1988年   65855篇
  1987年   64811篇
  1986年   61348篇
  1985年   58408篇
  1984年   44234篇
  1983年   37665篇
  1982年   22898篇
  1981年   20346篇
  1980年   19038篇
  1979年   41303篇
  1978年   28987篇
  1977年   24350篇
  1976年   22837篇
  1975年   23969篇
  1974年   29639篇
  1973年   28045篇
  1972年   26228篇
  1971年   24153篇
  1970年   22752篇
  1969年   21087篇
  1968年   19135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
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   
152.
153.
154.
A fluid-fiber-collagen stress tensor is used to describe the rheology of the left ventricle of the heart. Linear theory is used to find the equilibrium solutions for the end-diastolic and end-systolic states of general axisymmetric shapes that are small perturbations of a thick-walled finite cylinder. The general problem can be studied by superposing the effects of variable midwall radius but constant wall thickness with those of variable wall thickness but constant midwall radius. A Fourier series representation is used to describe the midwall radius and thickness functions. Numerical calculations are performed to determine the deformed geometry and spatial distributions of tissue pressure, stresses, and fiber strains. The calculations proved to be highly accurate when compared to an analytical solution obtained for the special case of no fibers. The results show significant longitudinal differences when compared to results for the cylindrical geometry, with more sensitivity to variation in wall thickness than to variation in midwall radius.  相似文献   
155.
A review of 96 consecutive patients who suffered neuro-ophthalmologic injuries in motorcycle accidents revealed a wide range of findings. These findings were similar to signs associated with other forms of closed-head trauma, aside from a higher incidence of trochlear nerve palsies.  相似文献   
156.
Up to now two abnormal nephrographic patterns have been described as a result of arterial hypotension as an adverse response to urographic contrast material. We would like to describe a third pattern.  相似文献   
157.
158.
159.
Using radioimmunoassay the authors investigated the plasma concentration of the immunoreactive atrial natriuretic factor (IR-ANF) and its content in the atria of 4-, 8-, 12-, 16-, and 20-weeks-old spontaneously hypertensive rats (SHR), and compared the results with data obtained in normotensive Wistar-Kyoto rats of the same age. With hypertension accelerating in SHR between the 8th and the 20th weeks of life, IR-ANF content in the atrium gradually decreased, and the plasma IR-ANF concentration increased. The decline in IR-ANF was due to its decrease primarily in the left atrium. Long-term (6-day) administration of synthetic ANF to SHR with fully developed hypertension led to normalization of BP. The results do not support the hypothesis that arterial hypertension in SHR is induced by a primary deficiency of ANF. The changes in IR-ANF in the atria and plasma occur rather as an adaptive and regulatory response to increasing BP. Prolonged administration of ANF to SHR had a hypotensive effect. Therapeutic application of ANF in man depends on the development of oral and long-acting analogues.  相似文献   
160.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号