全文获取类型
收费全文 | 17825篇 |
免费 | 1149篇 |
国内免费 | 134篇 |
专业分类
耳鼻咽喉 | 201篇 |
儿科学 | 500篇 |
妇产科学 | 478篇 |
基础医学 | 2682篇 |
口腔科学 | 333篇 |
临床医学 | 1443篇 |
内科学 | 4308篇 |
皮肤病学 | 399篇 |
神经病学 | 2313篇 |
特种医学 | 494篇 |
外科学 | 1717篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 968篇 |
眼科学 | 184篇 |
药学 | 1214篇 |
中国医学 | 39篇 |
肿瘤学 | 1802篇 |
出版年
2024年 | 29篇 |
2023年 | 207篇 |
2022年 | 450篇 |
2021年 | 758篇 |
2020年 | 412篇 |
2019年 | 521篇 |
2018年 | 677篇 |
2017年 | 499篇 |
2016年 | 566篇 |
2015年 | 644篇 |
2014年 | 780篇 |
2013年 | 1057篇 |
2012年 | 1496篇 |
2011年 | 1517篇 |
2010年 | 840篇 |
2009年 | 766篇 |
2008年 | 1263篇 |
2007年 | 1162篇 |
2006年 | 1050篇 |
2005年 | 937篇 |
2004年 | 855篇 |
2003年 | 764篇 |
2002年 | 584篇 |
2001年 | 129篇 |
2000年 | 102篇 |
1999年 | 116篇 |
1998年 | 127篇 |
1997年 | 71篇 |
1996年 | 56篇 |
1995年 | 57篇 |
1994年 | 51篇 |
1993年 | 27篇 |
1992年 | 52篇 |
1991年 | 52篇 |
1990年 | 47篇 |
1989年 | 44篇 |
1988年 | 31篇 |
1987年 | 39篇 |
1986年 | 34篇 |
1985年 | 35篇 |
1984年 | 21篇 |
1983年 | 21篇 |
1979年 | 18篇 |
1978年 | 10篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1973年 | 11篇 |
1971年 | 13篇 |
1969年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Oxygen consumption (VO2) measured by indirect calorimetry (Nellcor-Puritan-Bennett 7250; Carlsbad, CA, USA) has been compared with VO2 calculated by the Fick method in 22 volume-controlled ventilated general surgical patients in the early post-operative period. For 198 pairs of measurements, VO2 Fick and VO2 indirect calorimetry correlated significantly (y = 1.00x - 35.8, P = 0.0001, r = 0.77). VO2 indirect calorimetry was 212 +/- 32 mL min-1 and VO2 Fick was 177 +/- 41 mL min-1 (P = 0.0001). The bias was 35 +/- 26 mL min-1. This difference represents 16 +/- 13% of the total body VO2. VO2 calculated by the Fick method did not accurately predict VO2 measured by indirect calorimetry, and the two methods were not interchangeable. VO2 calculated by the Fick method underestimated VO2 as measured by indirect calorimetry by a systematic quantity that could be attributed, in part, to VO2 of the lung. Indirect calorimetry should be the preferred method for measuring total body VO2 in mechanically ventilated surgical patients. 相似文献
72.
Santini C 《Annales pharmaceutiques fran?aises》1999,57(1):10-5; discussion 27-8
Under this title will be recalled the responsibilities exerted by the Pharmaceutical Industry in two different fields: in the field of drug production, which has to meet the most rigorous constraints in matter of quality (Good Manufacturing Practices, quality assurance...) under supervision of the pharmaceutical structure; in the field of drug use: after the initial evaluation of the benefit/risk ratio, on which in based the drug registration, it is the responsibility of the Industry to contribute constantly to the good use of medicines and to its optimization (information of health professionals, patient information, pharmacovigilance, and if necessary sanitary safety measures...). 相似文献
73.
Rocco Cicciarello Maria E. Gagliardi Francesca Albiero Mario Mesiti Antonio d'Aquino Emilia Ciriaco Giovanni Germana Emanuele Cardia Domenico d'Avella 《Child's nervous system》1993,9(1):25-27
Employing quantitative autoradiography, pineal body glucose utilization (GU) was measured in daytime or at night in prepubertal (aged 1 month), adult (aged 3 months), and mature (over 12 months old) rats. In prepubertal and adult rats, in daytime, GU values within the pineal tissue were homogeneously distributed around 65 mol glucose/100 g per min. In prepubertal animals no significant variations in GU were observed between daytime and nocturnal measurements. A circadian metabolic rhythmicity was evident in adult rats, with a GU peak measured at 2 a.m. In mature animals, GU also varied between day and night, with an increment in the relative difference between the two values. The present investigation is the first to demonstrate that circadian metabolic rhythmicity is absent before sexual maturation while it is enhanced in 12-month-old rats. These changes in pineal energy metabolism with advancing age are intriguing in view of the concept that the pineal gland may be involved in functional changes occurring during the process of aging. 相似文献
74.
Alessandro Filla Giuseppe De Michele Francesca Cavalcanti Filippo Santorelli Lucio Santoro Giuseppe Campanella 《Journal of neurology》1991,238(3):147-150
Summary Three families are described which include members with typical Friedreich's disease (FD) and others who are ataxic but do not satisfy all the diagnostic criteria for that disease. In family A two patients have an early-onset, rapidly progressive FD, while two others have a late-onset, more benign form. In families B and C one member has typical FD, and another has a similar ataxic syndrome, except for preservation of knee jerks. Laboratory evaluation is consistent with the diagnosis of FD in all cases. FD diagnosis appears justified in secondary cases with late onset or preserved tendon reflexes, provided that the index case fulfils all diagnostic criteria. Whether the diagnosis of FD is tenable in sporadic atypical cases remains to be seen. Echocardiographic and neurophysiological examination may be valuable in classifying such cases. 相似文献
75.
Francesca Levi-Schaffer Naomi Riesel Dov Soffer Oded Abramsky Talma Brenner 《Molecular and chemical neuropathology / sponsored by the International Society for Neurochemistry and the World Federation of Neurology and research groups on neurochemistry and cerebrospinal fluid》1991,15(2):173-184
The number and functional reactivity of peritoneal mast cells (MCs) were evaluated in rats with experimental allergic encephalomyelitis (EAE). Cells were counted following staining with toluidine blue and activation was measured by B-hexosaminidase (B-hex) release. The number of detectable MCs and their capacity to release B-hex decreased significantly by 40 and 65%, respectively, as compared with normal controls just prior to the onset of clinical signs. These values returned to normal on clinical recovery. Preliminary data on MC counts performed on histological sections of rat brains with EAE suggested a similar pattern of response, i.e., an early decrease prior to disease onset with subsequent normalization on recovery. In an attempt to modify the course of EAE, rats were treated with the MC stabilizing agent nedocromil or with the MC activating agent, compound 48/80. Nedocromil induced a slight delay in the onset of EAE, but only when administered at the time of EAE induction. Compound 48/80 did not seem to affect the clinical course of the disease. Our results suggest that MCs are involved in the pathogenesis of EAE and may contribute to the induction of the disease rather than to the effector phase and its clinical expression. 相似文献
76.
The influence of lisuride on naloxone-induced withdrawal signs (wet shakes, escape attempts) was studied in morphine-dependent rats. Lisuride, injected IP at doses of 12.5 and 25 g/kg, inhibited wet shakes while not significantly altering escape attempts induced by naloxone (4 mg/kg IP). At higher doses (50 and 100 g/kg IP), lisuride's inhibitory effect on wet shakes persisted while escape attempts were actually potentiated with respect to control withdrawal rats. Increases in aggressive behavior were seen at all doses, and were dose-related. Haloperidol (0.3 mg/kg IP), administered 40 min before lisuride, did not modify the antagonistic effect on wet shakes, unlike sulpiride (40 mg/kg IP 30 min before lisuride), but at the same time blocked the increase in escape attempts and aggressiveness induced by lisuride. We suggest that lisuride modulates withdrawal signs by stimulation of dopamine receptors in the CNS. The effect of the dopamine mimetic N-n-propylnorapomorphine (NPA) on the same variables is reported as well as the influence of haloperidol on NPA, and a comparison between the effects of the two drugs is made. 相似文献
77.
Conzo G Caracò C D'Ardis A Fontanella T Amore A Santini L 《Il Giornale di chirurgia》2000,21(1-2):44-48
The authors report a case of follicular thyroid cancer in "hot nodule" with micronodular synchronous lung metastases. The treatment consisted in TT associated with radioiodine therapy at the dose of 170 mCi with remission of cancer after six months of follow-up. Follicular variant is a prognostic unfavorable factor such as synchronous or metachronous pulmonary metastases. In those patients prognostic unfavorable variants are also age over 40 years, a poor radiofixation capacity, and a lesion of diameter up 1 cm. A strictly instrumental follow-up is mandatory to obtain diagnosis in a subclinical stage. In such cases the radiometabolic therapy agree to a remission of cancer with high survival after many years. TT yet represents a "minimal" surgical treatment for an accurate radioisotopic diagnosis. 相似文献
78.
Lamberto Re Cinzia Corneli Emanuele Sturani Giancarlo Paolucci Francesca Rossini Olga Sonia León Gregorio Martínez Marica Bordicchia Quintilio Tomassetti 《Pharmacological research》2003,48(1):55-60
The St. John's Wort (Hypericum perforatum) extract (Hp) represents one of the most useful natural therapeutic agents in the treatment of moderate and mild depression. The antidepressant effects of Hp are different, by a molecular mechanism point of view, when compared to those of other antidepressant drugs and, we think, a further pharmacological characterization is needed. It is suggested that the neurochemical effects of Hp could be bind either to its activity on the uptake of some mediators in the central nervous system or to the inhibition of some enzymatic activity at the receptor level. The present study carried out with the loose patch clamp (LPC) in the mouse neuromuscular junction, indicates a potentiation of the acetylcholine (ACh) action at the mouse neuromuscular junction. The spontaneous release of ACh was unaffected by Hp indicating that neither presynaptic nor postsynaptic function are modified by Hp. Indeed, both the frequency and the amplitude of the miniature end-plate currents (mepcs) were unmodified by Hp. Furthermore, the mepcs decay time (tau), i.e. the apparent cholinergic channel life time, was significantly increased after Hp treatment. The other parameter affected was the amplitude of the evoked end-plate currents (epcs) which was constantly and in a dose dependent manner increased by Hp. These findings suggest a possible action of Hp on the acetylcholinesterase (AChE) in terms of a reduction of the degradation rate of ACh. 相似文献
79.
Giovanni Biggio Laura Dazzi Francesca Biggio Luisa Mancuso Giuseppe Talani Fabio Busonero Maria Cristina Mostallino Enrico Sanna Paolo Follesa 《European neuropsychopharmacology》2003,13(6):411
Here, we summarize recent data pertaining to the effects of GABAA receptor modulators on the receptor gene expression in order to elucidate the molecular mechanisms behind tolerance and dependence induced by these drugs. Drug selectivity and intrinsic activity seems to be important to evidence at the molecular level the GABAA receptor tolerance. On the contrary, we suggested that all drug tested are equally potentially prone to induce dependence. Our results demonstrate that long-lasting exposure of GABAA receptors to endogenous steroids, benzodiazepines and ethanol, as well as their withdrawal, induce marked effects on receptor structure and function. These results suggest the possible synergic action between endogenous steroids and these drugs in modulating the functional activity of specific neuronal populations. We report here that endogenous steroids may play a crucial role in the action of ethanol on dopaminergic neurons. 相似文献
80.
Soluble CD40 ligand plasma levels in lung cancer. 总被引:7,自引:0,他引:7
Mario Roselli Tommaso C Mineo Stefania Basili Francesca Martini Sabrina Mariotti Simona Aloe Girolamo Del Monte Vincenzo Ambrogi Antonella Spila Raffaele Palmirotta Roberta D'Alessandro Giovanni Davì Fiorella Guadagni Patrizia Ferroni 《Clinical cancer research》2004,10(2):610-614
PURPOSE: Tumor-induced platelet activation may cause the release of various cytokines, including CD40 ligand (CD40L). Activation of the CD40/CD40L pathway in human tumors may result in thrombin generation, which is known to be involved in angiogenesis. Thus, we investigated whether soluble (s)CD40L levels are increased in patients with lung cancer as a result of platelet and/or coagulation activation. EXPERIMENTAL DESIGN: Citrated plasma samples were obtained from 120 patients with different stages and histotypes of lung cancer and 60 age- and sex-matched control subjects. sCD40L, sP-selectin (marker of platelet activation), prothrombin fragment 1 + 2, and thrombin-antithrombin III complex levels (both markers of coagulative activation) were measured in all samples. RESULTS: Patients with lung cancer had median sCD40L levels higher than in control subjects (0.46 versus 0.13 ng/ml; P < 0.0001), although correlation with the stage of disease was not evident. Nonetheless, sCD40L levels were significantly higher in squamous cancer compared with adenocarcinoma (0.75 versus 0.27 ng/ml; P < 0.05). Moreover, median sCD40L levels were higher in stage IV compared with nonmetastatic squamous lung cancer (1.02 versus 0.61 ng/ml; P < 0.05). sCD40L levels significantly correlated with sP-selectin (P < 0.001), prothrombin fragment 1 + 2 (P < 0.001), or thrombin-antithrombin III complex (P < 0.05) in squamous lung cancer, but only sP-selectin (P = 0.011) was independently related to sCD40L. CONCLUSIONS: These findings indicate that elevated sCD40L levels can be preferentially found in patients with advanced squamous cancer and provide evidence that increased levels of this cytokine are associated to the occurrence of in vivo platelet activation. 相似文献