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   1279102篇
  免费   97819篇
  国内免费   1988篇
耳鼻咽喉   18424篇
儿科学   44387篇
妇产科学   35015篇
基础医学   182218篇
口腔科学   33594篇
临床医学   111293篇
内科学   258284篇
皮肤病学   28020篇
神经病学   100449篇
特种医学   51214篇
外国民族医学   660篇
外科学   196432篇
综合类   27048篇
现状与发展   1篇
一般理论   377篇
预防医学   95734篇
眼科学   27913篇
药学   94777篇
  2篇
中国医学   2422篇
肿瘤学   70645篇
  2018年   13136篇
  2017年   9967篇
  2016年   10902篇
  2015年   12373篇
  2014年   17169篇
  2013年   26231篇
  2012年   36038篇
  2011年   38069篇
  2010年   22805篇
  2009年   21819篇
  2008年   36661篇
  2007年   39265篇
  2006年   39519篇
  2005年   38456篇
  2004年   37609篇
  2003年   36459篇
  2002年   35808篇
  2001年   64004篇
  2000年   66526篇
  1999年   56420篇
  1998年   15139篇
  1997年   13762篇
  1996年   14199篇
  1995年   13454篇
  1994年   12769篇
  1993年   11790篇
  1992年   44571篇
  1991年   43470篇
  1990年   42220篇
  1989年   40118篇
  1988年   36899篇
  1987年   36240篇
  1986年   33626篇
  1985年   32281篇
  1984年   24144篇
  1983年   20273篇
  1982年   11729篇
  1981年   10693篇
  1980年   9516篇
  1979年   21344篇
  1978年   14825篇
  1977年   12534篇
  1976年   11695篇
  1975年   12625篇
  1974年   14666篇
  1973年   14119篇
  1972年   12947篇
  1971年   11731篇
  1970年   11050篇
  1969年   10024篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Thirty-four epileptic patients, aged 9 to 36, were submitted to A/EEG between May 1987 and July 1988. All patients had a thorough clinical and EEG work-up including long-term conventional EEG, afternoon polygraphic sleep recording and, in some cases, full-night EEG and video monitoring. Patients were divided into 2 groups: group I included 19 patients (18 with symptomatic partial epilepsy (SPE) and 1 with idiopathic generalized epilepsy (IGE) in whom no seizure had ever been recorded in spite of EEG recordings averaging a total of 16 hrs 10 min, awake and asleep); group II included 15 subjects (6 with SPE, 5 with IGE, 3 with symptomatic GE and 1 with undetermined epilepsy) in whom one or several seizures had been recorded. A/EEG was performed in order to: 1) obtain better clinical and EEG characterization of seizures, 2) study the circadian distribution of seizures, 3) verify the efficacy of drug treatment and, 4) establish the epileptic or non-epileptic nature of some ictal events. The results of A/EEG were considered positive in 52.63% of group I patients and in 93.33% of group II patients. The authors discuss the specific advantages of A/EEG vs conventional EEG: recording of seizures with random occurrence, of seizures accompanied by falls, checking the remission of seizures.  相似文献   
994.
We report that treatment of 2.2.15, a human hepatoblastoma-derived cell line in which hepatitis B virus is actively replicating, with the carbocyclic analogue of 2'-deoxyguanosine [Shealy, Y. F., O'Dell, C. A., Shannon, W. M. & Arnett, G. (1984) J. Med. Chem. 27, 1416-1421] resulted in the nearly complete cessation of viral replication, as monitored by the absence of both intracellular episomal and secreted viral DNAs and by the absence of viral DNA polymerase activity. The drug was nontoxic in concentrations up to 200 times the minimum effective inhibitory concentration.  相似文献   
995.
996.
Gastrin-17 induces hypocalcemia in the rat without stimulating calcitonin release. The gastrin-induced hypocalcemia persisted after thyroparathyroidectomy or parathyroidectomy. In contrast, gastrectomy or extirpation of the acid-producing part of the stomach prevented the hypocalcemic effect, suggesting the involvement of the proximal stomach in the gastrin-evoked lowering of blood calcium. The drop in blood calcium upon injection of gastrin-17 did not reflect a loss of calcium via the gastric juice or via the urine. Extracts of the acid-producing mucosa of the rat stomach had a hypocalcemic effect. The extracts were purified by gel chromatography and reversed-phase high-performance liquid chromatography. Digestion with leucine aminopeptidase destroyed the hypocalcemic activity, while trypsin had no effect, suggesting a peptide (or peptides) with an unprotected NH2 terminus and without basic amino acid residues (or with protected basic amino acids). Both gastrin-17 and the mucosal extract stimulated the uptake of 45Ca into bone (radius and sternum). Gastrin-17 was without effect in rats that had undergone gastrectomy, while the mucosal extract was equally effective in gastrectomized and unoperated rats. We suggest that the effects of gastrin-17 on blood calcium and on calcium transfer into bone are indirect and that gastrin-17 stimulates the release of a peptide hormone, tentatively named gastrocalcin, from the acid-producing mucosa of the stomach. Gastrocalcin stimulates the uptake of 45Ca into bone, thereby causing hypocalcemia.  相似文献   
997.
Three different sensory loss tests, for anaesthesia to light touch, for diminished pain sensation and for loss of thermosensation, were compared with histopathological examination results in the diagnosis of suspected tuberculoid leprosy in 120 individuals with 126 lesions. Though none of the 3 tests used in this study was found to be strikingly superior to any of the others, the results indicate potentially important differences in their usefulness in different subgroups of suspected patients. The methodological problems inherent in such studies are discussed.  相似文献   
998.
Glucocorticoid effects on kainic acid-induced motor seizures and wet dog shakes in rats were investigated by adrenalectomy and dexamethasone treatment. One-day adrenalectomy attenuated kainic acid-induced wet dog shakes and seizure activity. These effects were restored by dexamethasone. Administration of dexamethasone to non-adrenalectomized rats potentiated kainic acid-induced wet dog shakes and severity of seizure activity. These results suggest that glucocorticoids may play an important role in modulating the severity of kainic acid-induced seizures and wet dog shakes.  相似文献   
999.
Quantitative autoradiographic analysis was used to identify regions in the brain of the male primate where androgen binding sites may be involved in the actions of testosterone. Three days after castration, adult male rhesus monkeys received a subcutaneous injection of either dihydrotestosterone propionate (DHTP, 20 mg, n = 6), testosterone propionate (TP, 100 mg, n = 2), or oil vehicle (control males, n = 4). Three hours later, 5 mCi [3H]testosterone was administered as an i.v. bolus. At 60 min, brains were rapidly removed and the left halves were used for autoradiography. In control males, highest percentages of labeled neurons (20-84% using a rigorous Poisson criterion) were observed in the ventromedial, arcuate and premammillary nuclei (n.) of the hypothalamus, medial preoptic n., bed n. of stria terminalis, intercalated mammillary n., lateral septal n. and the medial, cortical and accessory basal n. of the amygdala. Pretreatment with DHTP eliminated labeling in androgen target tissues of the genital tract, and reduced the percentages of labeled neurons to 4-22% of control values in the arcuate, lateral septal, premammillary and intercalated mammillary n., indicating that in these regions testosterone acted predominantly at androgen binding sites. However, in the medial preoptic n., the ventromedial hypothalamic n. and the accessory basal amygdaloid n., DHTP pretreatment resulted in much less blocking which, together with other data, suggested that in these sites, testosterone's actions involved aromatization and interaction with estrogen-binding sites.  相似文献   
1000.
Modern identification of Neisseria gonorrhoeae may be either accomplished by direct detection of gonococcal antigen, i.e. without microbiological culturing, or, following culturing, by rapid culture confirmation. The direct detection of gonococcal antigen in an enzyme immuno-assay (Gonozyme) shows reduced specifity especially with mixed microbial flora, and decreased sensitivity with small numbers of organisms. Culture confirmation may be achieved by a rapid sugar degradation test (API----quadFERM+), by specific enzyme detection using chromogenic substrates (Gonochek II), or by demonstration of protein I specific for Neisseria gonorrhoeae by means of monoclonal antibodies (Mikrotrak, Phadebact monoclonal GC, Gonogen II). Detection of protein I is highly sensitive and specific in both the tests of immunofluorescence and coagglutination.  相似文献   
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