全文获取类型
收费全文 | 11297篇 |
免费 | 616篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 102篇 |
儿科学 | 281篇 |
妇产科学 | 146篇 |
基础医学 | 1726篇 |
口腔科学 | 271篇 |
临床医学 | 1045篇 |
内科学 | 2205篇 |
皮肤病学 | 258篇 |
神经病学 | 1509篇 |
特种医学 | 568篇 |
外科学 | 1477篇 |
综合类 | 49篇 |
一般理论 | 2篇 |
预防医学 | 578篇 |
眼科学 | 159篇 |
药学 | 770篇 |
中国医学 | 18篇 |
肿瘤学 | 799篇 |
出版年
2023年 | 47篇 |
2022年 | 103篇 |
2021年 | 199篇 |
2020年 | 130篇 |
2019年 | 181篇 |
2018年 | 237篇 |
2017年 | 167篇 |
2016年 | 261篇 |
2015年 | 304篇 |
2014年 | 408篇 |
2013年 | 458篇 |
2012年 | 724篇 |
2011年 | 727篇 |
2010年 | 473篇 |
2009年 | 480篇 |
2008年 | 689篇 |
2007年 | 721篇 |
2006年 | 771篇 |
2005年 | 742篇 |
2004年 | 700篇 |
2003年 | 658篇 |
2002年 | 574篇 |
2001年 | 162篇 |
2000年 | 145篇 |
1999年 | 130篇 |
1998年 | 169篇 |
1997年 | 109篇 |
1996年 | 85篇 |
1995年 | 79篇 |
1994年 | 79篇 |
1993年 | 60篇 |
1992年 | 77篇 |
1991年 | 49篇 |
1990年 | 47篇 |
1989年 | 48篇 |
1988年 | 47篇 |
1987年 | 53篇 |
1986年 | 38篇 |
1985年 | 38篇 |
1984年 | 50篇 |
1983年 | 47篇 |
1982年 | 32篇 |
1981年 | 25篇 |
1980年 | 29篇 |
1979年 | 20篇 |
1978年 | 31篇 |
1977年 | 24篇 |
1976年 | 27篇 |
1954年 | 25篇 |
1938年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
G. Hempel Sebastian Krümpelmann Antje May-Manke Barbara Hohenlöchter Gottfried Blaschke Heribert Jürgens Joachim Boos 《Cancer chemotherapy and pharmacology》1997,40(1):45-50
To contribute to effective and safe outpatient treatment, we investigated the metabolism of trofosfamide (Trofo) after oral
administration. We analyzed Trofo metabolism in 15 patients aged from 3 to 73 years who were treated with 150 or 250 mg/m2 Trofo in combination with etoposide. Serum samples were collected with 13 patients after oral administration, and Trofo and
its dechloroethylated metabolites were quantified by gas chromatography. Urine samples were collected from five patients and
analyzed by same method. Ifosfamide (Ifo) was the main metabolite in serum and urine (AUCTrofo:AUCIfo 1:13), whereas cyclophosphamide (Cyclo) was formed in smaller amounts (AUCIfo:AUCCyclo 18:1). Ifo and Cyclo were further oxidized in the chloroethyl side chains to form 2- and 3-dechloroethylifosfamide in varying
quantities. The urinary excretion of Trofo and its dechloroethylated metabolites amounted to about 10% of the total dose.
Our results confirm former in vitro observations about the metabolism of Trofo. The main side-chain metabolites Ifo and Cyclo
can be further activated by oxidation and formation of their respective phosphoramide mustards. Hence, Trofo is an interesting
agent for oral chemotherapy.
Received 21 July 1996 / Accepted: 11 November 1996 相似文献
83.
84.
85.
James Prah David Ashley Benjamin Blount Martin Case Teresa Leavens Joachim Pleil Frederick Cardinali 《Toxicological sciences》2004,77(2):195-205
Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation kinetics, 14 volunteers were exposed to 51.3 microg/ml MTBE dermally in tap water for 1 h, drank 2.8 mg MTBE in 250 ml Gatorade(R), and inhaled 3.1 ppm. MTBE for 1 h. Blood and exhaled breath samples were then obtained. Blood MTBE peaked between 15 and 30 min following oral exposure, at the end of inhalation exposure, and ~5 min after dermal exposure. Elimination by each route was described well by a three-compartment model (Rsq >0.9). The Akaike Information Criterion for the three-compartment model was smaller than the two-compartment model, supporting it over the two-compartment model. One metabolite, tertiary butyl alcohol (TBA), measured in blood slowly increased and plateaued, but it did not return to the pre-exposure baseline at the 24-h follow-up. TBA is very water-soluble and has a blood:air partition ratio of 462, reducing elimination by exhalation. Oral exposure resulted in a significantly greater MTBE metabolism into TBA than by other routes based on a greater blood TBA:MTBE AUC ratio, implying significant first-pass metabolism. The slower TBA elimination may make it a better biomarker of MTBE exposure, though one must consider the exposure route when estimating MTBE exposure from TBA because of first-pass metabolism. Most subjects had a baseline blood TBA of 1-3 ppb. Because TBA is found in consumer products and can be used as a fuel additive, it is not a definitive marker of MTBE exposure. These data provide the risk assessment process of pharmacokinetic information relevant to the media through which most exposures occur-air and drinking water. 相似文献
86.
Cerebrospinal anandamide levels are elevated in acute schizophrenia and are inversely correlated with psychotic symptoms. 总被引:7,自引:0,他引:7
Andrea Giuffrida F Markus Leweke Christoph W Gerth Daniela Schreiber Dagmar Koethe Johannes Faulhaber Joachim Klosterk?tter Daniele Piomelli 《Neuropsychopharmacology》2004,29(11):2108-2114
The endocannabinoids are a family of bioactive lipids that activate CB1 cannabinoid receptors in the brain and exert intense emotional and cognitive effects. Here, we have examined the role of endocannabinoid signaling in psychotic states by measuring levels of the endocannabinoid anandamide in cerebrospinal fluid (CSF) of acute paranoid-type schizophrenic patients. We found that CSF anandamide levels are eight-fold higher in antipsychotic-naive first-episode paranoid schizophrenics (n = 47) than healthy controls (n = 84), dementia patients (n = 13) or affective disorder patients (n = 22). Such an alteration is absent in schizophrenics treated with 'typical' antipsychotics (n = 37), which antagonize dopamine D2-like receptors, but not in those treated with 'atypical' antipsychotics (n = 34), which preferentially antagonize 5HT(2A) receptors. Furthermore, we found that, in nonmedicated acute schizophrenics, CSF anandamide is negatively correlated with psychotic symptoms (rS = -0.452, P = 0.001). The results suggest that anandamide elevation in acute paranoid schizophrenia may reflect a compensatory adaptation to the disease state. 相似文献
87.
88.
Joachim Marr Klaas Heinemann Andrea Rapkin 《International journal of gynaecology and obstetrics》2011,113(2):103-107
Objective
To determine the effects of ethinyl estradiol (EE)/drospirenone in a 24/4 regimen (24 days of active and 4 days of inactive pills) on functional impairment (affecting work, partnership, and social activities) in women with premenstrual dysphoric disorder (PMDD).Methods
The present study was a secondary analysis of a double-blind, randomized, parallel-design multicenter trial. Women received EE 20 μg/drospirenone 3 mg (n = 232) or placebo (n = 218) and completed the Daily Record of Severity of Problems (DRSP) scale daily.Results
The decrease in mean scores for all 3 DRSP functional impairment items (work, partnership, and social activities) from baseline to cycle 3 mirrored changes in the total DRSP symptom score; the greatest decreases were observed in cycle 1 with further small reductions through to cycle 3. The proportional mean decreases from baseline to cycle 1 for the 3 functional items ranged from 47% to 48%. For all 3 functional items, the mean reductions from baseline to cycle 1 (but not from cycle 1 to cycles 2 and 3) were significantly greater with EE/drospirenone than with placebo (P < 0.05).Conclusion
Ethinyl estradiol 20 μg/drospirenone 3 mg in a 24/4 regimen significantly improved functional impairment in women with PMDD. Symptoms improved in parallel. 相似文献89.
Gullbo J Lindhagen E Bashir-Hassan S Tullberg M Ehrsson H Lewensohn R Nygren P De La Torre M Luthman K Larsson R 《Investigational new drugs》2004,22(4):411-420
The novel alkylating dipeptide melphalanyl-p-L-fluorophenylalanine ethyl ester (J1) was evaluated for acute toxicity and antitumor activity in mice, with melphalan as a reference. To determine a safe and tolerable dose for efficacy studies the acute toxicity following intravenous injection in the tail vein was monitored using a 14-day schedule with up to four doses. The highest tested dose, 25 micromoles/kg, was considered close to this level, with minor effects on body weight gain but significant effects on hematological parameters. Melphalan and J1 appeared equitoxic with no statistically significant differences. Subsequently a mouse hollow fiber model was employed with subcutaneous implantation of fibers containing human tumor cells. Three different human tumor cell lines as well as two samples of primary human tumor cells (ovarian carcinoma and chronic lymphatic leukemia) were used as tumor models. At the dose level tested there was a marked and statistically significant decrease in both T-cell leukemia CCRF-CEM and small cell lung cancer NCI-H69 tumor cell growth and viability in response to J1 as compared with both placebo and melphalan treated groups. In primary ovarian carcinoma cells only J1 treatment resulted in significant tumor regression (net cell kill). In summary the results indicate that, despite an expected short half time in the blood circulation, the promising in vitro data from the previous studies of J1 seems translatable into the in vivo situation. At equal doses of alkylating units J1, compared to melphalan, was more active in the mouse hollow-fiber model, but showed similar general toxicity. 相似文献
90.
Michael E. Scheurer Philip J. Lupo Joachim Schüz Logan G. Spector Joseph L. Wiemels Richard Aplenc 《Pediatric hematology and oncology》2018,35(2):95-110
The Inaugural Symposium on Childhood Cancer Health Disparities was held in Houston, Texas, on November 2, 2016. The symposium was attended by 109 scientists and clinicians from diverse disciplinary backgrounds with interests in pediatric cancer disparities and focused on reviewing our current knowledge of disparities in cancer risk and outcomes for select childhood cancers. Following a full day of topical sessions, everyone participated in a brainstorming session to develop a working strategy for the continued expansion of research in this area. This meeting was designed to serve as a springboard for examination of childhood cancer disparities from a more unified and systematic approach and to enhance awareness of this area of need. 相似文献