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   1508篇
  免费   131篇
  国内免费   3篇
  1642篇
  2021年   10篇
  2019年   10篇
  2018年   18篇
  2016年   12篇
  2015年   19篇
  2014年   33篇
  2013年   53篇
  2012年   57篇
  2011年   77篇
  2010年   48篇
  2009年   40篇
  2008年   56篇
  2007年   59篇
  2006年   55篇
  2005年   59篇
  2004年   73篇
  2003年   65篇
  2002年   58篇
  2001年   61篇
  2000年   49篇
  1999年   44篇
  1998年   27篇
  1997年   17篇
  1996年   14篇
  1995年   12篇
  1994年   11篇
  1993年   16篇
  1992年   36篇
  1991年   27篇
  1990年   25篇
  1989年   33篇
  1988年   20篇
  1987年   31篇
  1986年   30篇
  1985年   39篇
  1984年   20篇
  1983年   30篇
  1982年   24篇
  1981年   21篇
  1980年   24篇
  1979年   25篇
  1978年   21篇
  1977年   32篇
  1976年   20篇
  1975年   12篇
  1974年   10篇
  1973年   12篇
  1972年   8篇
  1971年   8篇
  1966年   7篇
排序方式: 共有1642条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
We have examined the nonparallel changes in tampanic membrane temperatures (T ty) from the two ears in response to various changes in body and head positions. Upon assuming a lateral recumbent position, the T ty on the lower side increased while that on the upper side decreased. Pressure application over a wide area of the lateral chest only caused inconsistent and obscure asymmetric changes in T ty. A lateral flexion of the head with the subject sitting upright and a rotation of the head to the side in a supine position induced an increase in the T ty on the lower side compared to that on the upper side. The temperature and blood flow of the forehead often decreased on the lower side and increased on the upper side, although such responses were not always concomitant with the asymmetric changes in T ty. A dorsal flexion of the head with the subject in a reclining position caused a slight increase in the T ty, whereas raising the head upright induced a slight decrease in them. Two additional experiments were carried out with single photon emission computed tomography using 99mTc-hexamethylpropyleneamine oxime as tracer, and a slight, relative decrease in counts was noted in the right hemisphere during rotation of the head to the right. These results would strongly suggest that unilateral increases and decreases in T ty could have been caused by one-sided decreases and increases, respectively, in blood flow to the brain and/or the tympanic membrane, induced by a vasomotor reflex involving vestibular stimulation.  相似文献   
15.
16.
In order to investigate the re-epithelialization process during wound healing, the hair on the back of guinea pigs was shaved and then excisional wounds were made through the entire thickness of the skin. Histological changes were observed and changes in the expression of different cytokeratin polypeptides were examined using an immunohistochemical technique. Immunohisto chemical study revealed that the proliferating and migrating keratinocytes expressed the same cytokeratins as the basal cells of normal epidermis. In addition, the entire epidermis of fairly remote areas from the edges of the wound where no thickening was observed showed a temporarily abnormal staining pattern. The suprabasal cells in the regenerating epidermis temporarily expressed cytokeratins not only specific for suprabasal cells but also specific for basal cells. The cytokeratins expressed in normal basal keratinocytes were also present in the thickened granular layers. These data indicate that the expression of cytokeratins in the epidermal keratinocytes (even in fairly remote areas from the wound edges) changes during wound healing, that the origin of the migrating keratinocytes from the remaining epidermis seems to be the basal cells in the epidermis, and that the appearance of keratohyalin granules is not related to changes in cytokeratin expression.  相似文献   
17.
Summary Using the polymorphic DNA probes, ChdTC-15, ChdTC-114, pYNH24, and λTM-18, a DNA profiling system was developed that verified identities of individual cultured cell lines collected in the Japanese cell banks, JCRB, RCB, and IFO. These highly polymorphic DNA probes include both VNTR (Variable Number of Tandem Repeats) sequences and substantial lengths of unique regions. In the mixed probe system, several distinct bands from four to eight can be used for cell line identification. These bands were widely spread in a range of molecular sizes, and were stable and reproducible under stringent conditions of Southern blot hybridization. Because the DNA profile was specific for each individual human cell line, it is useful not only to authenticate many existing cultured cell lines but also to monitor their identity during propagation in a laboratory, and to confirm newly established lines as unique.  相似文献   
18.
Serum thyroid hormone concentrations, 1-thyroxine (T4), free T4 and 3,5,3'-l-triiodothyronine (T3) were measured in 213 patients of diabetes and analyzed their correlation with metabolic parameters, hyperglycemia and body weight. Haemoglobin A1 (HbA1) was used as an index of hyperglycemia. Body weight was expressed by relative body weight (body weight/standard weight). Among the thyroid hormones, only T3 had significant correlation with HbA1 and body weight (r = -0.476, P less than 0.01 and r = 0.369, P less than 0.01, respectively). Multivariable analysis of serum T3 by HbA1 and relative body weight gave the following regression equation. Serum T3 (ng/dl) = 108 + 0.362 x relative body weight (%) - 3.88 x HbA 1 (%). Though relative body weight had inverse correlation with HbA1, the contribution of the two metabolic parameters to the serum T3 was independent from each other. Our results confirm the previous reports that low T3 in diabetes correlates with severity of hyperglycemia and we report for the first time that serum T3 of diabetic patients has positive correlation with body weight, probably due to still available carbohydrate in spite of disturbances in the metabolism.  相似文献   
19.
Mobility of phospholipid hydrocarbons in the Escherichia coli B membrane fractions was studied by labeling phosphatidylethanolamine or phosphatidylglycerol in situ by biosynthetic incorporation of the spin label. For this purpose, CDP-diacylglycerol spin label was synthesized from phosphatidic acid spin label and cytidine 5'-phosphoromorpholidate and purified by thin-layer chromatography. DCP-diacylglycerol spin label was then incorporated into phospholipids biosynthetically. ESR spectra of these E. coli B membrane fractions showed that phosphatidylglycerol tended to interact with membrane proteins through the mediation of Mg2+, whereas phosphatidylethanolamine had less of this tendency and was more involved in the formation of the bulk of the bilayer continuum of the membrane. These conclusions were also supported by labeling membranes with exogenous spin-labeled phospholipids, although there was some indication that exogenous phospholipids were incorporated into sites different from the sites of incorporation of phospholipids newly synthesized in situ.  相似文献   
20.
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