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   5501篇
  免费   277篇
  国内免费   22篇
耳鼻咽喉   35篇
儿科学   111篇
妇产科学   80篇
基础医学   656篇
口腔科学   175篇
临床医学   387篇
内科学   1299篇
皮肤病学   135篇
神经病学   495篇
特种医学   229篇
外科学   698篇
综合类   30篇
预防医学   191篇
眼科学   109篇
药学   519篇
中国医学   39篇
肿瘤学   612篇
  2023年   36篇
  2022年   55篇
  2021年   115篇
  2020年   70篇
  2019年   64篇
  2018年   116篇
  2017年   79篇
  2016年   84篇
  2015年   97篇
  2014年   146篇
  2013年   173篇
  2012年   284篇
  2011年   310篇
  2010年   166篇
  2009年   152篇
  2008年   288篇
  2007年   311篇
  2006年   284篇
  2005年   312篇
  2004年   289篇
  2003年   273篇
  2002年   266篇
  2001年   116篇
  2000年   134篇
  1999年   129篇
  1998年   80篇
  1997年   55篇
  1996年   55篇
  1995年   55篇
  1994年   49篇
  1993年   49篇
  1992年   104篇
  1991年   102篇
  1990年   92篇
  1989年   85篇
  1988年   99篇
  1987年   68篇
  1986年   72篇
  1985年   76篇
  1984年   45篇
  1983年   56篇
  1982年   17篇
  1981年   23篇
  1979年   31篇
  1977年   22篇
  1975年   17篇
  1974年   18篇
  1973年   19篇
  1972年   20篇
  1967年   17篇
排序方式: 共有5800条查询结果,搜索用时 15 毫秒
111.
A party of 57 people dined together in a restaurant in Hamamatsu City on December 11, 2001. The next day, 22 of them developed symptoms of acute gastroenteritis, such as diarrhea, vomiting, and fever. Examination of 4 fecal specimens from these patients by ELISA for Norovirus (Norwalk-like virus, NV) detected both genogroup I (GI) and genogroup II (GII) NV in all the 4 specimens. In addition, RT-PCR and real-time PCR methods for NV detected the NV gene. Approximately one month after the outbreak of the food poisoning (acute gastroenteritis) by NV, 4 individuals in the same party developed type A hepatitis. Both RT-PCR and real-time PCR methods for hepatitis A virus (HAV) detected the HAV gene in their fecal specimens. The party of these patients ate purple Washington clam (Saxidomus purpuratus, imported from China) steamed with red pepper. Since this food appeared to have caused the viral infections, the one with the same lot number was subjected to viral examinations, which successfully detected the NV GI, NV GII, and HAV genes. These results led to the conclusion that the clam contaminated with NV and HAV had caused the food poisoning. The DNA sequences of the NV detected in the patients and the clam had 74 to 99% homology, indicating strains of various genotypes. All the strains of HAV that were derived from the patients and the clam were genotype 1A, and these sequences had over 95% homology, but were not completely identical. This outbreak led to the demonstration of imported fishery products as a cause of type A hepatitis, and indicated the need for guiding and enlightening people on the importance of adequate cooking of bivalves.  相似文献   
112.
Summary. The platelet antigen Naka was once considered to be a platelet-specific alloantigen and is carried on platelet membrane glycoprotein (GP) IV. Recent studies suggest that Naka-negative subjects lack platelet GPIV. GPIV is an important adhesive receptor and expressed on the surface of monocytes as well as of platelets. In the present study, flow cytometry was used to detect GPIV and Naka antigen on the surface of monocytes. Naka antigen was expressed on monocytes as well as on platelets in Naka-positive subjects ( n = 6) (P-GPIV-positive subjects). To our surprise, monocytes of Naka-negative subjects ( n = 7) (P-GPIV-negative subjects) having no anti-Naka antibody in their serum expressed GPIV and Naka antigen to almost the same degree as did the monocytes of P-GPIV-positive subjects. Competitive experiments using OKM5 (a monoclonal antibody against GPIV) and anti-Naka antibody showed that the epitope of anti-Naka antibody on monocytes was very close to that of OKM5. In two P-GPIV-negative subjects having anti-Naka antibody in their serum, GPIV and Naka antigen were not expressed on the surface of either monocytes or platelets. These results indicate that the GPIV molecules and Naka antigen are expressed on the surface of monocytes in the majority of P-GPIV-negative subjects, but that in a very few P-GPIV-negative subjects neither GPIV nor Naka antigen is expressed on the surface of their monocytes. We hypothesize that P-GPIV-negative subjects who carry neither GPIV nor Naka antigen on their monocytes produce anti-Naka antibody as a result of transfusion or pregnancy.  相似文献   
113.

Background

The onset of acute heart failure is known to be associated with increased physical activity and other specific behaviors that can trigger hemodynamic deterioration. This analysis aimed to describe the distribution of triggers in patients hospitalized for acute heart failure, and investigate their effects on in-hospital outcomes.

Methods

Consecutive patients hospitalized for acute heart failure between 2010 and 2014 were registered in a multicenter data registration system (72 institutions within Tokyo, Japan). Baseline demographics and in-hospital mortality were extracted from 17,473 patients. Patients with a trigger were grouped based on their triggering event: those with onset during (a) physical activity; (b) sleeping; (c) eating or watching television; (d) bathing or excretion (use of restrooms); and (e) engaging in other activities. These patients were compared with patients without identifiable triggers. Multiple imputation was used for missing data.

Results

Patients were predominantly men (57.1%), with a mean age of 76.0 ± 13.0 years; a triggering event was present in 49.1%. No significant difference in baseline characteristics was noted between groups except for younger age, higher blood pressure, and prevalence of signs of congestion in the trigger-positive group. In-hospital mortality rate was 7.9%. Presence of triggers was positively associated with a reduced risk of in-hospital mortality (adjusted odds ratio 0.79; 95% confidence interval, 0.70-0.90; P = .0003). In a delta-adjusted pattern mixture model, the effect of a triggering event on in-hospital mortality remained consistently significant.

Conclusion

Triggering events for acute heart failure can provide additional information for risk prediction. Efforts to identify the triggers should be made to classify patients according to risk group.  相似文献   
114.
OBJECTIVE: Despite multiple and repeated exposures to HIV-1, some individuals possess no detectable HIV genome and show T-cell memory responses to the viral antigens. HIV-1-reactive mucosal IgA detected in such uninfected individuals suggests their possible immune resistance against HIV. We tested if the above HIV-1-exposed but uninfected status was associated with genetic markers other than a homozygous deletion of the CCR5 gene. METHODS: Based on our mapping in chromosome 15 of a gene controlling the production of neutralizing antibodies in a mouse retrovirus infection, we genotyped 42 HIV-1-exposed but uninfected Italians at polymorphic loci in the syntenic segment of human chromosome 22, and compared them with 49 HIV-1-infected and 47 uninfected healthy control individuals by a closed testing procedure. RESULTS: A significant association was found between chromosome 22q12-13 genotypes and a putative dominant locus conferring anti-HIV-1 immune responses in the exposed but uninfected individuals. Distributions of linkage disequilibrium across chromosome 22 also differed between the exposed but uninfected and two other phenotypic groups. CONCLUSIONS: The data indicated the presence of a new genetic factor associated with the HIV-1-exposed but uninfected status.  相似文献   
115.
In neonatal cardiomyocytes, activation of the G(q)-coupled alpha(1)-adrenergic receptor (alpha(1)AR) induces hypertrophy by activating mitogen-activated protein kinases, including c-Jun NH(2)-terminal kinase (JNK). Here, we show that JNK activation is essential for alpha(1)AR-induced hypertrophy, in that alpha(1)AR-induced hypertrophic responses, such as reorganization of the actin cytoskeleton and increased protein synthesis, could be blocked by expressing the JNK-binding domain of JNK-interacting protein-1, a specific inhibitor of JNK. We also identified the classes and subunits of G proteins that mediate alpha(1)AR-induced JNK activation and hypertrophic responses by generating several recombinant adenoviruses that express polypeptides capable of inhibiting the function of specific G-protein subunits. alpha(1)AR-induced JNK activation was inhibited by the expression of carboxyl terminal regions of Galpha(q), Galpha(12), and Galpha(13). JNK activation was also inhibited by the Galpha(q/11)- or Galpha(12/13)-specific regulator of G-protein signaling (RGS) domains and by C3 toxin but was not affected by treatment with pertussis toxin or by expression of the carboxyl terminal region of G protein-coupled receptor kinase 2, a polypeptide that sequesters Gbetagamma. alpha(1)AR-induced hypertrophic responses were inhibited by Galpha(q/11)- and Galpha(12/13)-specific RGS domains, C3 toxin, and the carboxyl terminal region of G protein-coupled receptor kinase 2 but not by pertussis toxin. Activation of Rho was inhibited by carboxyl terminal regions of Galpha(12) and Galpha(13) but not by Galpha(q). Our findings suggest that alpha(1)AR-induced hypertrophic responses are mediated in part by a Galpha(12/13)-Rho-JNK pathway, in part by a G(q/11)-JNK pathway that is Rho independent, and in part by a Gbetagamma pathway that is JNK independent.  相似文献   
116.

The effects of the water extract of Sinomeni Caulis et Rhizoma (SCR-WE) and its major constituents, sinomenine (SIN) and magnoflorine (MAG), on moderate hemolysis induced by lysophosphatidylcholine (LPC) were investigated in rat erythrocytes and compared with the anti-hemolytic effects of lidocaine (LID) and propranolol (PRO) as reference drugs. LPC caused hemolysis at concentrations above the critical micelle concentration (CMC), and the concentration of LPC producing moderate hemolysis (60 %) was approximately 10 μM. SCR-WE at 1 ng/mL–100 μg/mL significantly inhibited the hemolysis induced by LPC. SIN and MAG attenuated LPC-induced hemolysis in a concentration-dependent manner from very low to high concentrations (1 nM–100 μM and 10 nM–100 μM, respectively). In contrast, the inhibiting effects of LID and PRO on LPC-induced hemolysis were observed at higher concentrations (1–100 μM) but not at lower concentrations (1–100 nM). Neither SIN nor MAG affected micelle formation of LPC, nor, at concentrations of 1 nM–1 μM, did they attenuate the hemolysis induced by osmotic imbalance (hypotonic hemolysis). Similarly, SCR-WE also did not modify micelle formation or hypotonic hemolysis, except at the highest concentration. These results suggest that SIN and MAG potently protect the erythrocyte membrane from LPC-induced damage and contribute to the beneficial action of SCR-WE. The protective effects of SIN and MAG are mediated by some mechanism other than prevention of micelle formation or protection of the erythrocyte membrane against osmotic imbalance.

  相似文献   
117.
118.
BACKGROUND: The development of well-matured fibrosis in usual interstitial pneumonia (UIP) is strongly associated with an unfavorable outcome of patients with idiopathic pulmonary fibrosis (IPF). However, differences in the rates of development are likely to result in variable clinical courses in IPF patients. OBJECTIVE: We tried to evaluate the progression of honeycombing and ground-glass opacity on CT using a scoring system, and to examine those serial changes in the clinical course of disease. METHODS: A hospital-based, retrospective cohort study. Twenty-three patients with IPF diagnosed as UIP by surgical lung biopsy were analyzed during the initial examination by scoring the presence of honeycombing (HC: range, 0-24) and ground-glass opacity (GG: range, 0-24) on CT scan. We also compared the serial changes observed in the CT scores (interval: 2-42 months, 2-6 examinations). RESULTS: (1) The serial change in the HC score in treated patients (n = 10) was similar to that in untreated patients (n = 16); (2) the HC score at the time of the initial examination and the rate of HC progression were both higher in the non-surviving patients (HC 12.3 +/- 3.7, mean +/- SD; deltaHC 4.2 +/- 1.3 per year) than in the surviving patients (HC 5.8 +/- 2.7; deltaHC 1.2 +/- 0.7 per year) (p < 0.05); (3) the GG score did not correlate with the HC score at any of the examinations; (4) the HC score was higher in the lower lung field than in the upper and middle lung fields. CONCLUSIONS: Scoring of the honeycombing and its serial changes using the high-resolution computed tomography scoring method was useful for predicting the prognosis in patients with IPF/UIP. Corticosteroid treatment did not prevent the progression of HC.  相似文献   
119.
Nagase analbuminemic rats (NARs) have a 7-base-pair deletion at the 5' splice site of the HI intron of the albumin gene. The level of immunohistochemically albumin-positive hepatocytes is about 1 per 10(5) cells in neonatal NARs, increases with age, and further increases with chronic oral treatment with 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB). The mechanisms involved in the increase in albumin-positive hepatocytes during aging of NARs and their treatment with 3'-MeDAB were analyzed. NARs were found to have four species of albumin mRNA: intact mRNA and those lacking the regions corresponding to exon H, exon G-H, and exon H-I. In 4-week-old NARs, the level of intact albumin mRNA was about 1/4000 of that in normal rats and mRNA lacking the exon H sequence was the major species. In aged and 3'-MeDAB-treated aged NARs, all four species of mRNA increased and the relative proportion of mRNAs lacking two exon sequences to mRNAs lacking one exon sequence was greatly increased, suggesting that aging is associated with changes of the splicing pattern and that 3'-MeDAB treatment enhanced these changes. In aged NARs and 3'-MeDAB-treated aged NARs, there was an increase in the amount of aberrant 60-kDa albumin. The 60-kDa protein could be a translation product of mRNAs lacking two exons, the amount of which increases in aged NARs and 3'-MeDAB-treated NARs.  相似文献   
120.
Although side-to-side isoperistaltic anastomosis is a useful strictureplasty technique when long segments of intestinal stenosis complicate Crohns disease, concerns have been raised regarding disease recurrence adjacent to the anastomosis. We performed side-to-side isoperistaltic anastomosis without spatulated intestinal ends as a method of reconstruction after intestinal resection for Crohns disease; both intestinal ends were transversely closed like a Heineke-Mikulicz-type strictureplasty. With this procedure, the luminal diameter proximal and distal to the anastomosis became wider than the original diameter of the intestine. This new procedure, which we refer to as the modified side-to-side isoperistaltic anastomosis with double Heineke-Mikulicz procedure could become an alternative operation after intestinal resection in persons with Crohns disease, although long-term outcome analysis is necessary.  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