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   11510篇
  免费   544篇
  国内免费   49篇
耳鼻咽喉   109篇
儿科学   366篇
妇产科学   102篇
基础医学   1612篇
口腔科学   351篇
临床医学   766篇
内科学   2802篇
皮肤病学   306篇
神经病学   1048篇
特种医学   351篇
外科学   1881篇
综合类   55篇
预防医学   373篇
眼科学   222篇
药学   776篇
中国医学   25篇
肿瘤学   958篇
  2023年   62篇
  2022年   93篇
  2021年   206篇
  2020年   114篇
  2019年   186篇
  2018年   230篇
  2017年   173篇
  2016年   188篇
  2015年   205篇
  2014年   265篇
  2013年   354篇
  2012年   568篇
  2011年   611篇
  2010年   333篇
  2009年   311篇
  2008年   497篇
  2007年   568篇
  2006年   528篇
  2005年   559篇
  2004年   553篇
  2003年   542篇
  2002年   590篇
  2001年   360篇
  2000年   388篇
  1999年   369篇
  1998年   145篇
  1997年   120篇
  1996年   112篇
  1995年   103篇
  1994年   83篇
  1993年   77篇
  1992年   250篇
  1991年   233篇
  1990年   212篇
  1989年   199篇
  1988年   164篇
  1987年   184篇
  1986年   156篇
  1985年   152篇
  1984年   107篇
  1983年   90篇
  1980年   42篇
  1979年   90篇
  1978年   71篇
  1977年   64篇
  1971年   61篇
  1969年   48篇
  1968年   55篇
  1967年   43篇
  1966年   44篇
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
41.
To examine the clinical characteristics of methamphetamine (MAP) psychosis in Japan, we evaluated 104 patients with MAP psychosis (80 men and 24 women) admitted to the closed psychiatric units of Tokyo Metropolitan Matsuzawa Hospital between 1988 and 1991. There has recently been a steep increase in the number of admissions for MAP psychosis, reflecting the growth of the epidemic of MAP abuse in Japan. Although more than half of the patients were discharged within one month, 16 patients were hospitalized for more than 3 months. Most of the patients showed paranoid psychotic state similar to schizophrenia, consistent with previous reports. Despite the abstinence from MAP and antipsychotic medication, psychotic symptoms tended to persist in some of the patients. The etiological role of MAP psychosis in the development of long-lasting psychotic state was discussed.  相似文献   
42.
The risk of cerebral infarction (CI) in an individual is dependent on the interplay between genetic risk factors and environmental influences. Binding of thromboxane A2 (TXA2) to its receptor (TP) modulates thrombosis/hemostasis and plays a significant role in the pathogenesis of CI. The aim of the present study was to investigate the relationship between human TP gene single nucleotide polymorphisms (SNPs) and haplotypes and CI in a Japanese population. A genetic association study was performed in 194 CI patients and 365 non-CI subjects by specifically characterizing 6 SNPs in the human TP gene (rs2271875, rs768963, rs2238634, rs11085026, rs4523 and rs4806942). Analysis demonstrated that there were significant differences in the overall distribution of genotypes and dominant or recessive models of rs2271875 and rs768963 between the CI and the non-CI groups. Multiple logistic regression analysis revealed that the C allele of rs768963 was significantly associated with CI (p = 0.029), even after adjusting for confounding factors (odds ratio: 2.41). Further, the C-T-C haplotype of rs768963-rs2238634-rs4806942 was significantly more frequent in the CI group (23.0%) than in the non-CI group (17.7%). These results suggest that specific SNPs and haplotypes may have utility as genetic markers for the risk of CI and that TP or a neighboring gene is associated with the increased susceptibility to CI.  相似文献   
43.
Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.  相似文献   
44.
In order to investigate the comparative fates of nivalenol (NIV) and 4-acetyl derivative of NIV (fusarenon-X, FX) in mice, 3H-FX or 3H-NIV was given p.o. to mice. Radioactivity was excreted mainly via the urine in mice given 3H-FX, but mainly via the feces in mice given 3H-NIV. The plasma radioactivity reached a peak at 30 or 60 min after the administration of 3H-FX or 3H-NIV, respectively. The plasma peak level was 5 times higher, and the area under curve (AUC) was 10 times higher, in 3H-FX-administered than 3H-NIV-administered mice. These findings clearly demonstrate that FX is absorbed from the gastrointestinal tract more rapidly and efficiently than NIV. The HPLC profile of radioactivity of acetonitrile extracts of urine and feces indicated that FX is rapidly metabolized to NIV after being absorbed from the gastrointestinal tract. In vitro incubation of tissue homogenates with 3H-FX demonstrated that the liver and kidney are the organs responsible for the FX-to-NIV conversion. Thus this study demonstrated that the higher oral toxicity of FX than NIV that has been observed in mice and rats is due to the efficient absorption of FX than NIV from the gastrointestinal tract, followed by its rapid conversion to NIV by the liver and kidney.  相似文献   
45.
The purpose of this study was to evaluate the acute effects of corticosteroid and iodide preoperative therapy in patients with Graves' disease in terms of thyroid function and immunological parameters. The above combination was prescribed for 4 patients who had experienced severe side effects from antithyroid drugs (ATD) in order to reduce the possibility of post-thyroidectomy thyroid storm. Corticosteroids were employed daily for four days, and iodides were given daily for two weeks prior to thyroidectomy. The free T3 values decreased rapidly to euthyroid levels following the administration of both drugs, although the free T4 values were still much higher than normal in 3 of the 4 patients at the time of surgery. By comparison, 3 of 8 patients treated with ATD also had thyroid hormone levels above normal. Studies of lymphocyte subsets revealed that the percentage of helper T cells was significantly less in the corticosteroidiodide treatment group than in the control and ATD groups. It is thus possible that postoperative thyroid storm might be prevented through corticosteroid-iodide therapy by virtue of the reduction of free T3 values to within the normal range by the time of surgery. The acute suppression of helper T cells was another result of this form of therapy observed.  相似文献   
46.
Summary: Purpose: We wished to assess the risk of terato-genicity of zonisamide (ZNS) in humans.
Methods: Pregnant epileptic women treated with ZNS and their offspring were prospectively monitored from June 1989 to December 1994. The outcome of pregnancy and status of neonates were examined based on the same standardized protocol.
Results: Twenty-six offspring exposed to ZNS with or without other antiepileptic drugs (AEDs) were studied. Malformations were detected in 2 offspring (7·7%) exposed to ZNS polypharmacy. Anencephaly was detected in one case at 16 weeks of gestation (case 1, artificial abortion), and atrial septa1 defect was detected in another case at 37 weeks of gestation (case 2, delivery by cesarean section). Serum concentrations of ZNS during the first trimester of pregnancy were 6·1 μg/ml in case 1 and 6·3μ/ml in case 2; in both cases, the levels were below the therapeutic concentration range of ZNS.
Conclusions: Teratogenic effects of ZNS were not clearly defined from these results since malformations were detected in two polypharmacy cases but not in four monopharmacy cases. The present data do not indicate that the risk of ZNS teratogenicity is greater than that of other conventional AEDs. However, such risk cannot be neglected even at therapeutic dosages or concentrations of ZNS, especially in patients receiving polypharmacy.  相似文献   
47.
C Farb  C Aoki  T Milner  T Kaneko  J LeDoux 《Brain research》1992,593(2):145-158
The ultrastructure and synaptic associations of terminals immunoreactive for L-glutamate (Glu) were examined in the lateral nucleus of the amygdala (AL). All results reported here involved tissue fixed only with paraformaldehyde. The specificity of the antiserum with paraformaldehyde fixation conditions was assessed and confirmed by immuno-dot blot analysis: the reactivity of anti-Glu to glutamic acid was at least 1,000 times greater than the reactivity to other amino acids. At the light microscopic level, Glu-immunoreactive punctate processes and somata were present in AL. At the electron microscopic level, many Glu-immunoreactive terminals were identified. Data analysis was performed on 365 of these labeled terminals. Glu-immunoreactive terminals were 0.3-1.5 microns in diameter and contained numerous small, clear vesicles as well as mitochondria. Many (77%) of the terminals analyzed had morphologically identifiable synaptic specializations. Most (90%) of the Glu-immunoreactive terminals with synaptic specializations formed asymmetric synapses on spines or small dendrites; synaptic specializations on soma or proximal dendrites were rarely seen (< 1%). Glu-immunoreactive terminals were qualitatively compared to terminals in AL labeled with two other antisera: anti-glutaminase, a marker for the enzyme that catalyzes the conversion of glutamine to the releasable or transmitter form of Glu, and anti-gamma-aminobutyric acid (anti-GABA), a marker for the major inhibitory amino acid transmitter in the brain. Terminals immunoreactive for glutaminase, like those immunoreactive for Glu, formed mostly asymmetric synaptic specializations on spines or small dendrites. In contrast, GABA-immunoreactive terminals usually formed symmetric synapses on soma or proximal dendrites and were never observed to form asymmetric axo-spinous contacts. Although Glu is a metabolic precursor to GABA, these data indicate that the majority of Glu-immunoreactive terminals reflect the site of synthesis and release of Glu and not of GABA. In addition, these results provide morphological evidence that Glu plays a role in excitatory neurotransmission at synapses in AL and support the growing body of data implicating excitatory amino acid-mediated synaptic plasticity in-emotional learning and memory processes in AL.  相似文献   
48.
A case of a cervical cancer in a 40-year-old woman with a plasma carcinoembryonic antigen (CEA) level of 29.4 ng/ml was investigated using light and electron microscopy. In addition, the plasma CEA levels before treatment were determined in 168 patients with cervical cancer and in 33 patients with endometrial cancer. CEA was found to be elevated in the plasma of 19% of those with cervical cancer and in 6% of those with endometrial cancer. Effective serial plasma CEA determinations following therapy, in patients whose plasma or tumors initially contain elevated amounts of antigen, might be useful as an adjunctive method in the earlier detection of a recurrent cancer.  相似文献   
49.
Thirteen patients with sickle cell disease (SCD) undergoing transfusion therapy and 8 control patients were examined by magnetic resonance imaging to discriminate bone marrow change due to iron deposition from hematologic marrow hyperplasia. Using T1-weighted spin echo images, only two subjects showed extremely low signal intensity marrow compatible with iron deposition. However, using T2-weighted fast spin echo images with fat suppression, cranial bone marrow in SCD patients with transfusion therapy showed considerably lower signal than that of controls. The main cause of marrow signal decrease in SCD patients with transfusion therapy was considered to be iron deposition due to repeated transfusion therapy rather than red marrow hyperplasia.  相似文献   
50.
It is known that benzodiazepines have a hypotensive effect, but the mechanism has not been well elucidated yet. To clarify whether this effect is due to central or peripheral mechanism, we administered 5 mg of diazepam or saline intravenously to healthy volunteers and assessed the change in blood pressure, heart rate, muscle sympathetic nerve activity and heart rate variability. After diazepam administration, systolic and mean blood pressure decreased significantly. Muscle sympathetic nerve activity was also significantly reduced but heart rate did not change, whereas the variables of spectral analysis of heart rate variability did not show significant change. We concluded that the hypotensive effect of diazepam in human is mainly due to the central mechanism.  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