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991.
Harm reduction strategies involve promoting a product that has adverse health consequences as a substitute for one that has more severe adverse health consequences. Smokeless tobacco low in nitrosamine content offers potential benefits in reducing smoking prevalence rates. Possible harm arises from the potential for such products to serve as a gateway to more harmful tobacco products, public misinterpretation of "less harmful" as "safe," distraction from the public health goal of tobacco elimination, and ethical issues involved in advising those marketing these harmful products. We offer a research agenda to provide a stronger basis for evaluating the risks and benefits of smokeless tobacco as a means of reducing the adverse health effects of tobacco.  相似文献   
992.
We report the case of a type II aortic dissection involving the pulmonary autograft after a Ross procedure 6 years earlier. A dissection flap was present in both the native ascending aorta and right coronary sinus of the autograft. At reoperation, the valve was spared using a root remodeling technique.  相似文献   
993.
994.
Whereas nitrosation of secondary amines produces nitrosamines, amino acids with primary amino groups and glycine ethyl ester were reported to react with nitrite to give unidentified agents that alkylated 4-(p-nitrobenzyl)pyridine to produce purple dyes and be direct mutagens in the Ames test. We report here that treatment of glycine ethyl ester at 37 degrees C with excess nitrite acidified with HCl, followed by ether extraction, gave 30-40% yields of a product identified as ethyl chloro(hydroximino)acetate [ClC(=NOH)COOEt, ECHA] and a 9% yield of ethyl chloroacetate. The ECHA was identical to that synthesized by a known method from ethyl acetoacetate, strongly alkylated nitrobenzylpyridine, and may have arisen by N-nitrosation of glycine ethyl ester to give ethyl diazoacetate, which was C-nitrosated and reacted with chloride to give ECHA. Nitrosation of ethyl diazoacetate also yielded ECHA. Ethyl nitroacetate was not an intermediate as its nitrosation did not produce ECHA. ECHA reacted with aniline to give ethyl (hydroxamino)(phenylimino)acetate [PhN=C(NHOH)CO2Et]. This product was different from ethyl [(phenylamino)carbonyl]carbamate [PhNHC(=O)NHCO2Et], which was synthesized by reacting ethyl isocyanatoformate (OCN.CO2Et) with aniline. ECHA reacted with guanosine to give a derivative, which may have been a guanine-C(=NOH)CO2Et derivative. ECHA showed moderate toxicity and weak but significant mutagenicity without activation in Salmonella typhimurium TA-100 (mean, 1.31 x control value for 12-18 microg/plats) and for V79 mammalian cells (1.5-1.7 x control value for 60-100 microM). In conclusion, gastric nitrosation of glycine derivatives such as peptides with a N-terminal glycine might produce ECHA analogues that alkylate bases of gastric mucosal DNA and thereby initiate gastric cancer.  相似文献   
995.
996.
Optimism and survival in lung carcinoma patients   总被引:2,自引:0,他引:2  
Schofield P  Ball D  Smith JG  Borland R  O'Brien P  Davis S  Olver I  Ryan G  Joseph D 《Cancer》2004,100(6):1276-1282
BACKGROUND: It is popular belief that the psychologic response to a diagnosis of cancer influences survival in patients with cancer; however, research has produced contradictory results. In this prospective study, the authors investigated the relation between pretreatment levels of optimism and survival in patients with nonsmall cell lung carcinoma (NSCLC). METHODS: Two hundred four patients who were participating in a randomized trial that compared accelerated and conventional radiotherapy with and without carboplatin chemotherapy were asked to complete two questionnaires assessing optimism. The first assessment was just prior to commencing treatment and the second assessment took place after completing treatment. Survival was measured from the date of randomization to the date of death. Surviving patients were followed until February 8, 2001. RESULTS: The pretreatment questionnaire was completed by 179 patients, and 148 of those patients completed the posttreatment questionnaire. There was a small but significant reduction in optimism scores after treatment (P = 0.005). There was no association noted between pretreatment optimism and progression-free survival (P = 0.52, unadjusted; P = 0.22, adjusted for Eastern Cooperative Oncology Group performance status and patient age), nor was there an association noted between pretreatment optimism and overall survival (P = 0.36, unadjusted; P = 0.19, adjusted for disease stage). CONCLUSIONS: There was no evidence that a high level of optimism prior to treatment enhanced survival in patients with NSCLC. Encouraging patients to "be positive" only may add to the burden of having cancer while providing little benefit, at least in patients with NSCLC.  相似文献   
997.
The data of the National Polyp Study, a large longitudinal study on surveillance of adenoma patients, is used for testing assumptions on the adenoma-carcinoma sequence. The observed adenoma and colorectal cancer incidence in the National Polyp Study were compared with the simulated outcomes of the MISCAN-COLON model of epidemiology and control of colorectal cancer for the U.S. population based on expert opinion. Variants of this model were explored in order to identify assumptions on the adenoma-carcinoma sequence that are consistent with the study observations. The high observed adenoma detection rates at surveillance and low observed colorectal cancer incidence in the National Polyp Study could only be explained by assuming a high incidence rate of adenomas accompanied by regression of adenomas. The National Polyp Study data suggest that adenoma prevalence results from a dynamic process of both formation as well as regression of adenomas. This lowers the expectations for the effects of colorectal cancer screening strategies that focus on adenoma detection.  相似文献   
998.
A rare source of potentially massive lower gastrointestinal hemorrhage in women is advanced gynecologic malignancy. Such patients can develop gastrointestinal hemorrhage with or without prior pelvic irradiation, due to arteriocolic fistulas. Angiography permits the correct diagnosis and subsequent embolotherapy.  相似文献   
999.
A crude CH(2)Cl(2)-MeOH extract prepared from Commiphora africana was found to mediate Cu(2+)-dependent relaxation of supercoiled plasmid DNA. Bioassay-guided fractionation of this extract was carried out and was monitored by the use of an in vitro DNA strand scission assay. The dihydroflavonol glucoside phellamurin (1) was identified as the active principle responsible for the DNA cleavage activity of the crude extract.  相似文献   
1000.
OBJECTIVE: To outline the clinical and polysomnographic changes induced by nefazodone in patients with seasonal affective disorder. METHODS: Twelve patients were enrolled, and 9 of them studied, in an open-label trial with objective and subjective measurements. The mean age of the studied patients was 45 (range 35-58) years. They met Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria for major depressive disorder and current major depressive episode with seasonal patterns. The patients' mean baseline score on the Seasonal Patterns Assessment Questionnaire (SPAQ) was 15.7 (standard deviation [SD] 5.3). The total nefazodone treatment period was 8 weeks, and the daily dosages were 100 mg in week 1, 200 mg in week 2, 300 mg in week 3, and up to 400 mg in weeks 4-8. Each patient received the 29-item version of the Hamilton Rating Scale for Depression (HAM-D), the Hamilton Rating Scale for Anxiety (HAM-A) and 2-night polysomnographic assessments on 3 occasions: before treatment (baseline, W0), at the end of week 4 (W4) and at the end of week 8 (W8). RESULTS: There were statistically significant improvements in depression, anxiety, sleep latency and sleep efficiency during the 8-week treatment protocol. Repeated-measures analysis of variance results indicated that nefazodone has a time-dependent effect on both HAM-D and HAM-A scores. After 8 weeks of nefazodone therapy, HAM-D scores decreased from 33.4 (SD 8.1) to 11.6 (SD 5.6) (F(2,14) = 13.68, p = 0.001) and HAM-A decreased from 26.6 (SD 7.0) to 11.5 (SD 11.1) (F(2,14) = 13.46, p = 0.001). The results of paired t tests show that, compared with baseline, HAM-D and HAM-A scores decreased at both W4 (p = 0.004 and p = 0.002, respectively) and W8 (p = 0.002 and p = 0.005, respectively). The time-dependent effects on stage 1 sleep (F(2,16) = 6.06, p = 0.011) and periodic leg movement index (F(2,16) = 4.31, p = 0.035) were also significant. The mean sleep latency of these patients decreased from 39.9 (SD 32.7) minutes at W0 to 16.6 (SD 15.3) minutes at W8 (p < 0.05). Sleep efficiency increased from 78.8% (SD 14.6%) at W0 to 91.5% (SD 5.5%) at W8 (p < 0.05). Stage 1 sleep decreased from 4.9% (SD 1.9%) at W0 to 3.4% (SD 2.6%) at W8 (p < 0.05). CONCLUSIONS: The results of this preliminary study indicate that nefazodone not only has favourable antidepressant and anxiolytic effects but also enhances sleep efficiency and sleep latency.  相似文献   
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