全文获取类型
收费全文 | 2143452篇 |
免费 | 156885篇 |
国内免费 | 5015篇 |
专业分类
耳鼻咽喉 | 30601篇 |
儿科学 | 68508篇 |
妇产科学 | 61943篇 |
基础医学 | 304794篇 |
口腔科学 | 63162篇 |
临床医学 | 187748篇 |
内科学 | 415542篇 |
皮肤病学 | 48974篇 |
神经病学 | 170152篇 |
特种医学 | 84359篇 |
外国民族医学 | 720篇 |
外科学 | 327957篇 |
综合类 | 50789篇 |
现状与发展 | 6篇 |
一般理论 | 794篇 |
预防医学 | 158210篇 |
眼科学 | 50485篇 |
药学 | 158970篇 |
6篇 | |
中国医学 | 4537篇 |
肿瘤学 | 117095篇 |
出版年
2018年 | 20362篇 |
2016年 | 18164篇 |
2015年 | 20483篇 |
2014年 | 28458篇 |
2013年 | 43467篇 |
2012年 | 56992篇 |
2011年 | 60576篇 |
2010年 | 36188篇 |
2009年 | 34695篇 |
2008年 | 57421篇 |
2007年 | 61859篇 |
2006年 | 62821篇 |
2005年 | 60632篇 |
2004年 | 59103篇 |
2003年 | 57199篇 |
2002年 | 55769篇 |
2001年 | 99653篇 |
2000年 | 102274篇 |
1999年 | 86407篇 |
1998年 | 23710篇 |
1997年 | 21512篇 |
1996年 | 21038篇 |
1995年 | 20046篇 |
1994年 | 18753篇 |
1993年 | 17434篇 |
1992年 | 68189篇 |
1991年 | 66253篇 |
1990年 | 65302篇 |
1989年 | 63572篇 |
1988年 | 58598篇 |
1987年 | 58246篇 |
1986年 | 55222篇 |
1985年 | 52809篇 |
1984年 | 39562篇 |
1983年 | 33513篇 |
1982年 | 20116篇 |
1981年 | 18301篇 |
1979年 | 37552篇 |
1978年 | 26955篇 |
1977年 | 23245篇 |
1976年 | 21333篇 |
1975年 | 23546篇 |
1974年 | 28228篇 |
1973年 | 27295篇 |
1972年 | 25813篇 |
1971年 | 24111篇 |
1970年 | 22763篇 |
1969年 | 21684篇 |
1968年 | 20168篇 |
1967年 | 18105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Double-blind, placebo-controlled comparison of clonazepam and alprazolam for panic disorder 总被引:1,自引:0,他引:1
G E Tesar J F Rosenbaum M H Pollack M W Otto G S Sachs J B Herman L S Cohen S A Spier 《The Journal of clinical psychiatry》1991,52(2):69-76
To test the reported antipanic efficacy of clonazepam, the authors randomized 72 subjects with panic disorder to 6 weeks of treatment with either alprazolam, clonazepam, or placebo. Endpoint analysis demonstrated a significant beneficial effect of both active treatments, but not placebo treatment, on the frequency of panic attacks, overall phobia ratings, and the extent of disability. Comparison of the two active treatments revealed no significant differences and no consistent tendency for one agent to be favored over another, although power to detect small differences was limited. Sedation and ataxia were the most common side effects reported, but these effects were mild and transient and did not interfere with treatment outcome. The results of this double-blind, placebo-controlled trial are consistent with previous reports of clonazepam's antipanic efficacy. 相似文献
942.
Lithium treatment of chronic hair pulling 总被引:3,自引:0,他引:3
G A Christenson M K Popkin T B Mackenzie G M Realmuto 《The Journal of clinical psychiatry》1991,52(3):116-120
Ten patients with chronic hair pulling received trials of lithium carbonate of 2 to 14 months' duration. Eight patients demonstrated decreased hair pulling and mild to marked hair regrowth. Three responders experienced increased hair pulling subsequent to discontinuation of lithium treatment. Lithium's effect on hair pulling may be related to its observed benefits in treating aggressivity, impulsivity, and mood instability. 相似文献
943.
The effect of haemodilution without volume expansion (isovolemic haemodilution) was assessed with respect to blood flow and oxygen transport across stenotic lesions of progressive severity in the dog carotid artery. As the mean haematocrit (Hct) was reduced from 40 +/- 1% (+/- SEM) to 32 +/- 0% (p less than 0.001), reductions in vascular resistance were significant across the 90% (p less than 0.001) and 95% (p less than 0.0003) relative carotid stenoses. Isovolemic haemodilution reduced fresh blood viscosity significantly by 27 +/- 3% (p less than 0.001) and 42 +/- 4% (p less than 0.001) at the low shear rates of 10 sec-1 and 1 sec-1 which are typical of low-flow states. Following a 20% reduction in Hct 30 to 35% increase (p less 0.001) in carotid blood flow occurred at non-critical degrees of stenosis while a mean 83% increase (p less than 0.001) occurred at the highly critical 95% relative stenosis. Oxygen transport after a 22% decrease in blood haemoglobin was significantly increased by 28% (p less than 0.01) at the 95% relative stenosis level. These data provide a physiologic rationale for the beneficial effects of haemodilution in acute cerebral ischaemia, cerebral vasospasm and cerebral revascularization or carotid endarterectomy. 相似文献
944.
The experimental infection of immunocompetent and immunodeficient athymic mice with an avirulent encephalitogenic Toxoplasma strain (DX strain) was employed to study the ensuing encephalitic process by use of histological and immunocytochemical methods. In the acute phase of the infection Toxoplasma cysts and tachyzoites were accompanied by an infiltrate composed of macrophages, CD4+ and CD8+ T cells. In the chronic stage a granulomatous encephalitis developed. In contrast to immunocompetent NMRI mice, athymic nude NMRI mice died 3 weeks post-infection because of a generalized toxoplasmosis with predominant involvement of the brain. A salient feature of murine Toxoplasma encephalitis was up-regulation of class I and II major histocompatibility complex (MHC) gene products. Class I antigen was widely expressed on microglial cells and astrocytes. Class II antigen was only expressed on microglial cells despite a considerable astrogliosis. Our results indicate a differential expression of MHC-determined antigens on brain cells in acute and chronic murine Toxoplasma encephalitis. 相似文献
945.
H S Ozaki K Iwahashi M Tsubaki Y Fukui Y Ichikawa Y Takeuchi 《Journal of neuroscience research》1991,28(4):518-524
The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
946.
947.
Total gastrectomy is discussed as the operation of choice among different surgical approaches for gastric carcinoma. We prefer the performance of an elective total gastrectomy with systematic lymphadenectomy (compartments I and II) and obligatory splenectomy. A retrospective study of 1,704 consecutive cases of gastric carcinomas showed a better outcome following total gastrectomy in relationship to distal subtotal gastrectomy, but these results cannot be used as evidence because of the lack of a prospective study. Nevertheless, a precise analysis of our cases in regard to tumor site and tumor type could show a frequency of only 6% to maximally 30%, in which elective total gastrectomy may represent a procedure too extensive to justify for an oncological course. 相似文献
948.
949.
A family with two members (two generations) exhibiting Turner syndrome is described. Cytogenetic studies on these individuals showed the presence of multiple X chromosome changes. Evidence is presented to show that the maternally inherited X chromosome is the chromosome involved in the structural alterations observed. The effect of a tendency of the maternal X chromosome to break at specific sites on the development of the Turner phenotype and abnormal karyology is discussed. 相似文献
950.