全文获取类型
收费全文 | 4875篇 |
免费 | 263篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 98篇 |
儿科学 | 259篇 |
妇产科学 | 81篇 |
基础医学 | 565篇 |
口腔科学 | 117篇 |
临床医学 | 320篇 |
内科学 | 967篇 |
皮肤病学 | 118篇 |
神经病学 | 193篇 |
特种医学 | 243篇 |
外国民族医学 | 1篇 |
外科学 | 646篇 |
综合类 | 262篇 |
一般理论 | 3篇 |
预防医学 | 177篇 |
眼科学 | 243篇 |
药学 | 549篇 |
1篇 | |
中国医学 | 9篇 |
肿瘤学 | 319篇 |
出版年
2023年 | 36篇 |
2022年 | 62篇 |
2021年 | 136篇 |
2020年 | 83篇 |
2019年 | 80篇 |
2018年 | 128篇 |
2017年 | 117篇 |
2016年 | 115篇 |
2015年 | 146篇 |
2014年 | 166篇 |
2013年 | 210篇 |
2012年 | 332篇 |
2011年 | 324篇 |
2010年 | 207篇 |
2009年 | 197篇 |
2008年 | 284篇 |
2007年 | 308篇 |
2006年 | 249篇 |
2005年 | 182篇 |
2004年 | 161篇 |
2003年 | 167篇 |
2002年 | 122篇 |
2001年 | 79篇 |
2000年 | 108篇 |
1999年 | 105篇 |
1998年 | 70篇 |
1997年 | 56篇 |
1996年 | 58篇 |
1995年 | 42篇 |
1994年 | 42篇 |
1993年 | 30篇 |
1992年 | 51篇 |
1991年 | 54篇 |
1990年 | 45篇 |
1989年 | 58篇 |
1988年 | 47篇 |
1987年 | 36篇 |
1986年 | 55篇 |
1985年 | 45篇 |
1984年 | 35篇 |
1983年 | 24篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 19篇 |
1979年 | 27篇 |
1977年 | 20篇 |
1975年 | 20篇 |
1974年 | 23篇 |
1972年 | 28篇 |
1967年 | 18篇 |
排序方式: 共有5171条查询结果,搜索用时 15 毫秒
91.
Reduced risk of upper gastrointestinal ulcer complications with celecoxib, a novel COX-2 inhibitor 总被引:13,自引:0,他引:13
Goldstein JL Silverstein FE Agrawal NM Hubbard RC Kaiser J Maurath CJ Verburg KM Geis GS 《The American journal of gastroenterology》2000,95(7):1681-1690
OBJECTIVE: The aim of this study was to assess the rate of upper gastrointestinal (UGI) ulcer complications (bleeding, perforation, or gastric outlet obstruction) associated with celecoxib, a specific COX-2 inhibitor, compared with the rate associated with nonspecific, nonsteroidal anti-inflammatory drugs (NSAIDs). METHODS: A pooled analysis was conducted of 14 multicenter, double-blind, randomized, controlled trials (RCTs) and a separate analysis of one long-term open label trial that assessed the efficacy and safety of celecoxib for symptomatic treatment of arthritis. The RCTs enrolled 11,008 patients with osteoarthritis or rheumatoid arthritis treated for 2-24 wk; the long-term open label trial enrolled 5,155 patients receiving celecoxib for a maximum of 2 yr. In the RCTs, patients were randomly assigned to receive placebo (n = 1,864; 208 patient-years), celecoxib 25-400 mg b.i.d. (n = 6,376; 1,020 patient-years), or a comparator NSAID (n = 2,768; 535 patient-years); NSAIDs were naproxen 500 mg b.i.d., diclofenac 50 or 75 mg b.i.d., or ibuprofen 800 mg t.i.d.). In the long-term, open-label trial, patients received celecoxib 100-400 mg b.i.d. for up to 2 yr (n = 5,155; 5,002 patient-years). The principal outcome measure of this analysis was development of a UGI ulcer complication, which was prospectively defined as bleeding, perforation, or gastric outlet obstruction. Ulcer complications were assessed and adjudicated by persons blinded to the patient's treatment assignment or the study in which the patient participated. RESULTS: In the RCTs, UGI ulcer complications occurred in no placebo patients (0 of 1,864 patients), in 2 of 6,376 celecoxib patients (0.03%), and in 9 of 2,768 patients receiving an NSAID (0.33%), corresponding to annual incidences of 0.20% for celecoxib (p > 0.05 vs placebo) and 1.68% for NSAIDs (p = 0.002 vs celecoxib and placebo). In the long-term open-label trial, nine UGI ulcer complications occurred, for an incidence of 0.17% and an annualized incidence of 0.18%. CONCLUSIONS: The incidence of UGI ulcer complications associated with celecoxib was 8-fold lower than with nonspecific NSAIDs. The incidence of ulcer complications observed in celecoxib-treated patients was similar to that in patients receiving placebo in the RCTs, and to that in non-NSAID users reported in the literature. 相似文献
92.
93.
M Shahid A Malik M Akram L M Agrawal A U Khan M Agrawal 《International journal of infectious diseases》2008,12(3):256-264
BACKGROUND: The beta-lactam antibiotics, in combination with aminoglycosides, are among the most widely prescribed antibiotics. However, because of extensive and unnecessary use, resistance to these drugs continues to increase. In recent years, resistance in the Indian bacterial population has increased markedly, the majority showing complex mechanisms. Due to increased transcontinental movement of the human population, it would be wise to know the prevalence and resistance complexity of these strains, well in advance, in order to formulate a policy for empirical therapy. METHODS: One hundred and eighty-one isolates of Escherichia coli and 61 isolates of Klebsiella pneumoniae obtained from 2655 non-repeat samples of pus (912) and urine (1743) were studied, and their resistance rates and patterns were noted. The isolates were analyzed for prevalent aminoglycoside and cephalosporin resistance phenotypes and for the presence of extended spectrum beta-lactamase (ESBL) and AmpC enzymes by spot-inoculation and modified three-dimensional tests developed in our laboratory. Fourteen isolates of E. coli and six of K. pneumoniae, resistant to all of the antibiotics tested, were selected for plasmid screening, curing, and transconjugation experiments, and for comparative evaluation of the double disk synergy test (DDST) and modified three-dimensional test (TDT) for detection of beta-lactamases. RESULTS: Urinary E. coli isolates showed maximum susceptibility to amikacin (57.1%), followed by tobramycin (38.5%) and gentamicin (31.9%). Eighteen (19.8%) isolates were susceptible to cefotaxime, whereas 11 (12.1%) were susceptible to ceftriaxone. The K. pneumoniae isolates from urine samples showed maximum susceptibility to tobramycin (63.6%) followed by amikacin (54.5%). Of the K. pneumoniae isolates, 31.8% were susceptible to cefotaxime and 13.6% were susceptible to ceftriaxone. A more or less similar trend of antibiotic susceptibility was noted in E. coli and K. pneumoniae isolates from pus samples. Twenty-six (14.4%) E. coli and 15 (24.6%) K. pneumoniae isolates were found to be ESBL-producers by NCCLS-ESBL phenotypic confirmatory test. Eighteen (9.9%) E. coli and 19 (31.1%) K. pneumoniae isolates were found to be AmpC enzyme-producers by our modified TDT. The simultaneous occurrence of ESBL and AmpC enzymes was noted in 7.7% and 9.8% isolates of E. coli and K. pneumoniae, respectively. CONCLUSIONS: The prevalence of multidrug-resistant bacterial isolates is quite high in our bacterial population. On comparative evaluation of DDST and TDT in resistant isolates, TDT was found to be the better method, detecting ESBLs in 80% of isolates compared to 15% with DDST. A 19.9-kb plasmid was consistently present in all the screened isolates of E. coli and K. pneumoniae, and was inferred to encode cefoxitin and tetracycline resistance based on curing and transconjugation experiments. 相似文献
94.
We have investigated the protective effect of oral terfenadine, a H1 antagonist, on the dermal and pulmonary response, and changes of circulating WBCs to injected and inhaled platelet activating factor. Nine men with mild asthma participated in a double-blind, crossover study using terfenadine, 120 mg, or placebo. Three hours after administration of study drug, pulmonary function was measured, and a PAF challenge was performed. Skin test to histamine and PAF was performed prior to study drug, and 2.5 hours after drug. Circulating WBC count was determined prior to PAF inhalation and during the PAF challenge. There was a significant improvement in pulmonary function on terfenadine. Terfenadine significantly inhibited the wheal and flare response to histamine and the flare response to injected PAF. Terfenadine did not have an effect on the change in circulating WBC count or the change in pulmonary function to inhaled PAF. These results suggest a limited role for endogenous histamine for the effects of PAF. 相似文献
95.
Upper gastrointestinal mucosal lesions in chronic renal failure. 总被引:1,自引:0,他引:1
The upper gastrointestinal mucosa was studied endoscopically in 182 patients (140 males, 42 females) with chronic renal failure prior to hemodialysis. Endoscopy revealed normal mucosa in 77 patients (42.3%), inflammatory mucosal lesions in 88 (48.4%), peptic ulcer in 16 (8.8%; duodenal 15, gastric 1) and Barrett's ulcer in one patient. Upper gastrointestinal bleeding was noted at presentation in 16 (8.8%) cases and was associated with erosive gastritis, duodenitis and duodenal ulcer in 11, 3 and 2 patients respectively. Thus patients with chronic renal failure had a high prevalence of inflammatory mucosal changes. 相似文献
96.
Effect of platelet-activating factor inhalation on nonspecific bronchial reactivity in man 总被引:1,自引:0,他引:1
Bronchial hyperactivity is a recognized hallmark of asthma, characterized by an exaggerated bronchial response to numerous mediators, including histamine. It is also well recognized that bronchial hyperresponsiveness is increased following allergen exposure, although no particular mediator has been shown to induce this response. The recent observation that PAF can induce increased nonspecific bronchial reactivity in normal subjects emphasizes its importance as an inflammatory mediator. In this report we sought to further elucidate the role of PAF in airway hyperreactivity by comparing the effect of PAF on methacholine-induced airway responsiveness in six non-asthmatic subjects. Nonspecific airway responsiveness was not significantly increased following PAF inhalation at 6 hours nor was it increased at 1, 2, 7, or 14 days. Further elucidation of the potential role of PAF in explaining changes in airway reactivity is necessary. 相似文献
97.
Bacteremia after upper gastrointestinal endoscopy. 总被引:5,自引:0,他引:5
A L Baltch I Buhac A Agrawal P O'Connor M Bram E Malatino 《Archives of internal medicine》1977,137(5):594-597
During 24 months, 200 upper gastrointestinal endoscopies were performed on 193 patients. Blood cultures were obtained before and five and 30 minutes after the procedure using thiol (50 ml) and trypticase soy broth (100 ml) media. The mean endoscopic time was 34 minutes. Sixteen patients developed bacteremia (8%). Twelve groups of microorganisms were detected in positive blood cultures: Streptococcus (5 species), Lactobacillus sp, Veillonella alcalescens, Staphylococcus aureus, Staph epidermidis, Propioni-bacterium acnes, Corynebacterium acnes, and Bacillus subtilis. Seven patients had positive blood cultures at five and 30 minutes, eight at five minutes, and one at 30 minutes only. There was no clear correlation of bacteremia with the age or previous history of the patient, biopsy, active bleeding, endoscopic time, or findings. A follow-up study of all patients for six months to two years indicated no complications related to endoscopy and/or bacteremia. 相似文献
98.
Agrawal NM Campbell DR Safdi MA Lukasik NL Huang B Haber MM 《Archives of internal medicine》2000,160(10):1455-1461
BACKGROUND: The usefulness of nonsteroidal anti-inflammatory drugs (NSAIDs) is limited by adverse gastrointestinal tract events. OBJECTIVE: To identify the optimal antisecretory therapy for healing of gastric ulcer in patients using NSAIDs and the impact of concurrent Helicobacter pylori infection on ulcer healing. DESIGN: Prospective, double-blind, multicenter, parallel-group study. SETTING: Gastroenterology practices in ambulatory and referral center settings. PATIENTS: Three hundred fifty-three patients with an active, nonmalignant gastric ulcer at least 5 mm in diameter confirmed by endoscopy and biopsy and who continued to receive stable doses of NSAIDs. INTERVENTION: Patients were randomized to receive ranitidine hydrochloride, 150 mg twice daily, or lansoprazole, 15 mg or 30 mg once daily, for 8 weeks. MEASUREMENTS: Healing was assessed by endoscopy at 4 and 8 weeks in an intent-to-treat population. Helicobacter pylori status was assessed by histological examination. RESULTS: After 8 weeks of treatment, healing was observed in 61 (53%) of 115, 81 (69%) of 118, and 85 (73%) of 117 patients receiving ranitidine lansoprazole, 15 mg, and lansoprazole, 30 mg, respectively (P<.05 for ranitidine vs both lansoprazole doses; 95% confidence interval, 3.2-28.0 for ranitidine vs lansoprazole, 15 mg, and 7.4-31.8 for ranitidine vs lansoprazole, 30 mg). The gastric ulcer healing rates were similar between H pylori-infected and -noninfected patients, with a statistically significant increase with the use of lansoprazole vs ranitidine. CONCLUSIONS: In patients who require continuous treatment with NSAIDs, lansoprazole is superior to ranitidine for healing of NSAID-associated gastric ulcers. Healing is not delayed by the presence of H pylori infection. 相似文献
99.
Oligodeoxynucleoside phosphoramidates and phosphorothioates as inhibitors of human immunodeficiency virus 总被引:26,自引:15,他引:26 下载免费PDF全文
S Agrawal J Goodchild M P Civeira A H Thornton P S Sarin P C Zamecnik 《Proceedings of the National Academy of Sciences of the United States of America》1988,85(19):7079-7083
Modified oligodeoxynucleotides complementary to RNA of human immunodeficiency virus 1 (HIV-1) were tested for their ability to inhibit virally induced syncytium formation and expression of viral p24 protein. The modifications of oligomers include replacement of backbone phosphodiester groups with phosphorothioates and various phosphoramidates. All oligomers were found to be active. Oligomers with complete replacement of phosphodiesters with phosphoramidate or phosphorothioate groups were more active at the micromolar range than were unmodified oligomers of the same sequence. In addition, modified and unmodified homooligonucleotides also showed inhibition of HIV-1 replication. It is suggested that different classes of oligonucleotides may inhibit HIV replication by different mechanisms. 相似文献
100.
Baulch Janet E. Acharya Munjal M. Agrawal Sudhanshu Apodaca Lauren A. Monteiro Clarice Agrawal Anshu 《Journal of neuroimmune pharmacology》2020,15(4):852-862
Journal of Neuroimmune Pharmacology - This study examines the link between peripheral immune changes in perpetuation of the Alzheimer’s disease (AD) neuropathology and cognitive deficits. Our... 相似文献