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   46901篇
  免费   56篇
  国内免费   89篇
耳鼻咽喉   199篇
儿科学   836篇
妇产科学   1689篇
基础医学   6618篇
口腔科学   2111篇
临床医学   2144篇
内科学   11230篇
皮肤病学   875篇
神经病学   3449篇
特种医学   1054篇
外科学   10385篇
综合类   353篇
预防医学   1226篇
眼科学   664篇
药学   3432篇
中国医学   201篇
肿瘤学   580篇
  2023年   7篇
  2022年   74篇
  2021年   346篇
  2020年   31篇
  2019年   2177篇
  2018年   1371篇
  2017年   533篇
  2016年   20篇
  2015年   24篇
  2014年   38篇
  2013年   52篇
  2012年   40篇
  2011年   62篇
  2010年   106篇
  2009年   25篇
  2008年   36篇
  2007年   37篇
  2006年   36篇
  2005年   15篇
  2004年   27篇
  2003年   83篇
  2002年   9篇
  2001年   75篇
  2000年   79篇
  1999年   102篇
  1998年   14篇
  1997年   9篇
  1996年   17篇
  1995年   32篇
  1994年   13篇
  1992年   20篇
  1991年   14篇
  1988年   23篇
  1985年   3874篇
  1984年   5351篇
  1983年   4090篇
  1982年   4455篇
  1981年   4179篇
  1980年   3504篇
  1979年   3595篇
  1978年   2837篇
  1977年   2151篇
  1976年   2458篇
  1975年   1884篇
  1974年   1631篇
  1973年   1459篇
  1972年   23篇
  1971年   2篇
  1968年   1篇
  1934年   1篇
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
901.
HLA antigens (A, B, C and DR loci), serum islet cell antibodies, thyrogastric antibodies, and insulin antibodies were studied in 77 families (25 simplex, 42 multiplex, and 10 multigenerational). In order to test for intrafamilial constancy and intergroup variation, we compared simplex with multiplex families, HLA identical and non identical siblings within families, as well as groups of families characterized by different DR alleles (DR3, DR4, and DR3/DR4) for various immunologic and clinical characteristics. These comparisons did not reveal all the distinct subgroups suggested by different cross-sectional population studies, but did provide evidence for a compound form having an aggregation of different high risk alleles. This study suggests that in many cases (and possibly especially in families with multiple affected individuals), there are several different genetic influences leading to IDDM.  相似文献   
902.
The families of 12 probands with classic mitral valve prolapse were studied for evidence of mitral valve prolapse. Seventy parents, sibs, and progeny were included in the analysis. Forty-seven percent (16 of 34) of progeny were affected compared with 30 percent (3 of 10) of parents. Thirty-eight percent (10 of 26) of sibs were affected. A three-compartmental penetrance model was devised to account for the variation in expression with age. This includes a latent stage (time before onset of signs), an affected stage, and a stage in which the subjects are withdrawn (because of treatment, regression, or death). The implications of this model are discussed.  相似文献   
903.
Despite the fact that heterogeneity of diabetes in man has become more and more evident in recent years, its pancreatic pathology is still represented by two distinct entities, roughly corresponding to the classic juvenile-onset and maturity-onset types of the disease.In juvenile-onset, insulin-dependent diabetes, the pancreatic islets show severe and pathognomonic changes. B cells are greatly reduced in number already at clinical onset. Contrary to classic opinion they do not always disappear in the years to follow. Insulin's, a common finding in the pancreas of recent onset juvenile diabetic subjects, is compatible with a viral infection as well as with an autoimmune reaction as the cause of B cell destruction. In the pancreas of juvenile-onset diabetic subjects the islets, which in the past have been regarded as atrophic and inactive, are actually composed of cells containing glucagon and somatostatin. There is also a profound distortion of islet organization, and many endocrine cells are scattered as single cells in the exocrine tissue. These findings may well account for the abnormal secretory behavior of the glucagon-secreting A cells in insulin-dependent juvenile-onset diabetes.In maturity-onset, noninsulin-dependent diabetes, the pancreatic pathology is extremely variable and not pathognomonic. A numeric reduction of the B cells can be demonstrated in many maturity-onset diabetic subjects, but this reduction is much more moderate than in insulin-dependent juvenile-onset diabetic subjects and does not account for the disease. The same amount of B cell reduction can be found in many elderly subjects without clinical evidence of diabetes. In many maturity-onset diabetic subjects, the cytologic characteristics of the B cells suggest a decreased responsiveness to the stimulus of hyperglycemia. Islet fibrosis and hyalinosis (amyloidosis), although common, cannot explain this secretory dysfunction. The exact site of the defect in the B cells of maturity-onset diabetic subjects remains to be defined. Further investigations are necessary to assess the role of disturbed intraislet intercellular relationships in the pathogenesis of late-onset diabetes.The dual pattern of islet pathology in diabetes in man does not preclude a more profound heterogeneity in the etiology and pathogenesis of the disease.  相似文献   
904.
905.
During a protocol study for the evaluation of patients with primary aldosteronism, a variety of diagnostic studies were employed in an attempt to identify patients with primary aldosteronism and to differentiate patients with adrenal adenoma from patients with idiopathic adrenal hyperplasia. In this study, we are able to demonstrate the utility of (1) absent postural increase in plasma aldosterone concentration, (2) adrenal scanning and (3) normalization of blood pressure with spironolactone therapy in identifying patients with primary aldosterone excess who have an adrenal adenoma, surgical removal of which results in eliminating their hypertension.  相似文献   
906.
We describe a 15 1/2 year old presenting with primary amenorrhea, hirsutism, acanthosis nigricans and insulin resistance. Ovarian vein catheterization studies revealed bilateral excess plasma testosterone and androstenedione secretion, and at surgery multiple dermoid cysts of both ovaries were found in association with polycystic ovaries. The suggestion that the dermoid cysts may be causative in the evolution of the polycystic ovarian disease has been made. The mechanism of the insulin resistance appears to be at the post receptor level. The acanthosis nigricans diminished following surgery with normalization of the plasma androgens.  相似文献   
907.
In two patients with terminal renal failure, manifestations of disease developed in multiple organ systems. One had a previous diagnosis of multiple myeloma with kappa light chain proteinemia and proteinuria. The other had idiopathic lobular glomerulonephritis. Hepatic and neurologic abnormalities developed in both; in the latter gastrointestinal, cardiac and endocrine disease developed as well. Clinical and pathologic correlations suggest that the retention and tissue deposition of light chains produced the organ dysfunction, inasmuch as free kappa light chain determinants were demonstrated histologically in the clinically affected organs. The deposition in these patients may be an extreme example of a common but previously unrecognized form of plasma cell dyscrasia.  相似文献   
908.
Thyroxine treatment improves some of the defective thermogenic properties of obese (ob/ob) mice. Because brown adipose tissue (BAT) is an important thermogenic organ in mice, effects of thyroxine treatment on Na+, K+-ATPase, a thyroid-hormone responsive enzyme, and on rates of norepinephrine (NE) turnover, an indicator of sympathetic nervous system activity, in BAT of lean and obese mice were evaluated. Female mice, six weeks old, were injected with approximately 4 micrograms thyroxine daily for 2 weeks. Numbers of Na+, K+-ATPase enzyme units in BAT were similar in control lean and obese mice. Thyroxine treatment increased numbers of Na+, K+-ATPase enzyme units by 60% and 100% in lean and obese mice, respectively, indicating that the BAT of obese mice was responsive to thyroxine treatment. Fractional rates of NE turnover were 75% faster in BAT of control lean mice than in obese mice. Thyroxine treatment decreased functional rates of NE turnover in BAT of lean mice by 35%, but had no effect on NE turnover in BAT of obese mice. Rates of NE turnover in heart and pancreas of control lean and obese mice were unaffected by phenotype. Although the decreases in fractional rates of NE turnover in heart (-23%) and pancreas (-11%) of lean mice in response to thyroxine injections were not statistically significant, the calculated rates of NE turnover (fractional rate of NE turnover times the NE content of the organ) in these organs of lean mice were decreased 25% to 30% (P less than 0.05) in response to thyroxine. Thyroxine injections did not affect NE turnover in either heart or pancreas of obese mice.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
909.
Three patients with hemiagenesis of the typhoid gland are described. One was clinically euthyroid, whereas the other two were more unusual in that one had coincident Graves' disease with thyrotoxicosis, and one had primary myxodema. In all three cases diagnosis of hemiagenesis was established by the administration of thyroid-stimulating hormone (TSH). The literature on hemiagenetic thyroid glands with and without associated thyroid disease is reviewed. Although the anomaly is uncommon, awareness and recogniton of its existence may clarify an otherwise puzzling clinical thyroid evaluation, and thus possible avert an unnecessary surgical procedure.  相似文献   
910.
Described here is a case of multiple myeloma in a patient with sickle cell anemia. Viscometric studies were made by comparing the patient's whole blood, plasma and washed red blood cells with those of a normal control subject and a patient with sickle cell anemia. Results showed that the increased viscosity of the patient's whole blood as compared with that of the control patient with sickle cell anemia was mainly due to erythrocytic Interaction with the circulating abnormal immunoglobulin. It is postulated that the increased frequency of vaso-occlusive crisis that occurred in our patient in the months before the diagnosis and treatment of multiple myeloma, was due to this cell-protein interaction with the resulting enhancement of whole blood viscosity and the sickling phenomena.  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