全文获取类型
收费全文 | 3569篇 |
免费 | 336篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 91篇 |
妇产科学 | 121篇 |
基础医学 | 569篇 |
口腔科学 | 110篇 |
临床医学 | 346篇 |
内科学 | 661篇 |
皮肤病学 | 73篇 |
神经病学 | 305篇 |
特种医学 | 283篇 |
外科学 | 595篇 |
综合类 | 106篇 |
一般理论 | 3篇 |
预防医学 | 209篇 |
眼科学 | 101篇 |
药学 | 161篇 |
中国医学 | 24篇 |
肿瘤学 | 119篇 |
出版年
2021年 | 35篇 |
2018年 | 47篇 |
2017年 | 38篇 |
2016年 | 34篇 |
2015年 | 48篇 |
2014年 | 72篇 |
2013年 | 99篇 |
2012年 | 124篇 |
2011年 | 122篇 |
2010年 | 88篇 |
2009年 | 75篇 |
2008年 | 116篇 |
2007年 | 140篇 |
2006年 | 130篇 |
2005年 | 114篇 |
2004年 | 117篇 |
2003年 | 101篇 |
2002年 | 104篇 |
2001年 | 101篇 |
2000年 | 103篇 |
1999年 | 91篇 |
1998年 | 75篇 |
1997年 | 63篇 |
1996年 | 58篇 |
1995年 | 48篇 |
1994年 | 47篇 |
1993年 | 38篇 |
1992年 | 68篇 |
1991年 | 68篇 |
1990年 | 81篇 |
1989年 | 93篇 |
1988年 | 93篇 |
1987年 | 81篇 |
1986年 | 67篇 |
1985年 | 83篇 |
1984年 | 53篇 |
1983年 | 43篇 |
1982年 | 43篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 46篇 |
1978年 | 35篇 |
1977年 | 49篇 |
1976年 | 31篇 |
1975年 | 39篇 |
1974年 | 45篇 |
1973年 | 38篇 |
1972年 | 40篇 |
1970年 | 44篇 |
1968年 | 43篇 |
排序方式: 共有3912条查询结果,搜索用时 0 毫秒
41.
Integration of viral into chromosomal deoxyribonucleic acid in an inducible line of polyoma-transformed cells 总被引:10,自引:0,他引:10
RNA-DNA hybridization has shown that in poiyoma-transformed rat cells which can be induced to synthesize infectious virus (LPT cells), polyoma DNA sequences are associated with chromosomal DNARNA complementary to the viral DNA (cRNA) was synthesized in vitro, using purified viral DNA as a template and Escherichia coli RNA polymerase. High-molecular-weight chromosomal DNA was fractionated from linear and supercoiled viral DNA molecules by centrifugation of whole cells through alkaline glycerol gradients. Hybridization carried out between the cRNA and fractionated chromosomal DNA showed that the amount of RNA hybridized to the LPT DNA was two to three times larger than the amount hybridized to DNA from normal rat cells. cRNA was also hybridized, under the same conditions, with mixtures containing a constant amount of normal cell DNA and varying quantities of purified viral DNA. These assays have established that a linear relationship exists between the amount of cRNA specifically hybridized with a given sample of DNA and the quantity of viral DNA in the sample. Using this relationship, it is estimated that LPT chromosomal DNA contains 6–9 genome-equivalents of polyoma DNA per cell. This quantity represents 18–29% of the amount of polyoma DNA found in the cells, as determined by hybridization of cRNA with unfractionated LPT DNA.To exclude the possibility that the chromosomally associated viral DNA is an artifact due to incomplete removal of the extrachromosomal viral DNA, control experiments were performed in which the cells were superinfected with polyoma virus (m.o.i.-500; 3 hr infection). In these experiments, less than 1% of the viral DNA introduced into the cells by the superinfecting virus were found by the same techniques to be associated with chromosomal DNA. Other experiments show that LPT cells do not contain significant amounts of complex viral DNA molecules which sediment in the vicinity of chromosomal DNA. It is therefore suggested that viral and chromosomal DNA are bound to each other by bonds which cannot be disrupted by alkali treatment. 相似文献
42.
The human B lymphoblastoid cell line FPA was established from a consanguineous individual homozygous for the unusual serologically defined Class II genotype, DR5+, MB1+, (MB3-), MT2+. The MB1 allodeterminant is classically found only in association with DR1, 2, or w6 and DR5 is almost invariably associated with MB3. Class II molecules expressed by this unusual DR5 homozygous cell line have been characterized by immunochemical analysis using two-dimensional gel electrophoresis. These molecules were isolated from the FPA cell line by anti-DR5, anti-MT2, and anti-MB1 allosera, as well as a monoclonal antibody which defines an MB1-like determinant. However, an anti-MB3 alloserum and a monoclonal antibody which defines an MB3-like determinant did not immunoprecipitate Class II molecules from FPA. These studies document that the MB1 allodeterminant resides on DS molecules from this DR5 cell line and provide additional evidence that MB1 and MB3 are alleles of the same Class II antigen system. 相似文献
43.
双—对二甲氨基苯甲醛缩二胺类希夫碱合成、表征及抗菌活性 总被引:9,自引:1,他引:8
目的:合成双-对二甲氨基苯甲醛缩二胺类希夫碱,并对其抗菌活性进行研究。方法:以对二甲氨基苯甲醛和二胺类为原料,经缩合反应,制得4种相应希夫碱。结果:结构经元素分析、红外光谱、核磁共振谱确定,4种化合物均未见文献报道,抗菌活性测试表明,它们具有一定抗菌活性。结论:乙酸是催化剂,对缩合反应有利,希夫碱化合物具有一定抗菌活性。 相似文献
44.
Nicole E. Sharp MD FACS Darren B. Sachs DO Nicole M. Melchior DO Philip Albaneze MD FACS Salvatore Nardello DO Elin R. Sigurdson MD PhD FACS Mengying Deng MMath Allison A. Aggon DO FACOS John M. Daly MD FACS Richard J. Bleicher MD FACS 《The breast journal》2021,27(4):335-344
Prospective trials demonstrate that sentinel node (SN) biopsy after neo-adjuvant chemotherapy (NACT) has a significant false-negative rate (FNR) when only 1 or 2 SNs are removed. It is unknown whether this increased FNR correlates with an elevated risk of recurrence. Tumor Registry data at an NCI-Designated Comprehensive Cancer Center were reviewed from 2004 to 2018 for patients having a negative SN biopsy after NACT. Among 190 patients with histologically negative nodes after NACT having 1 (n = 42), 2 (n = 46), and ≥3 (n = 102) SNs, axillary recurrences occurred in 7.14%, 0%, and 1.96% (p = 0.09), breast recurrences occurred in 2.38%, 6.52%, and 0.98% (p = 0.12), and distance recurrences occurred in 16.67%, 8.70%, and 7.84% (p = 0.27), respectively. Time to first recurrence did not differ by SN count (p = 0.41). After adjustment for age, race, clinical stage, and receptor status, there were no differences in the rates of axillary (p = 0.26), breast (p = 0.44), or distance recurrence (p = 0.24) by numbers of SNs harvested. Median follow-up was 46.8 months. Despite higher post-NACT FNRs reported in randomized trials for patients having <3 sentinel nodes, recurrence rates were not significantly different for 1 versus 2 versus ≥3 SNs. This suggests that patients having 1 or 2 post-NACT SNs identified may not necessitate axillary dissection. 相似文献
45.
46.
47.
M. Sachs A. Encke 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1993,378(5):288-291
Zusammenfassung Es wird über eine 43jährige Patientin berichtet, die mehrere Wochen lang über inkonstant auftretende, krampfartige Mittelbauchschmerzen klagte. Die Diagnose einer ileoilealen Invagination konnte bei der Patientin erst beim dritten stationären Aufenthalt gestellt werden. Folgende Fehldiagnosen waren während des 4wöchigen Verlaufs bei der Patientin gestellt worden: Nierenbeckenentzundung, acute Appendizitis, chronische Appendizitis und zuletzt psychosomatische Bauchschmerzen. Die Patientin wurde zunächst antibiotisch, zuletzt mit Psychopharmaka medikamentös behandelt. Schließlich wurde die Diagnose einer Invagination des Dünndarms mittels Sonographie vermutet und in der konventionellen fortlaufenden Magen-Darm-Passage röntgenologisch gesichert. Bei der Patientin wurde daraufhin eine Dünndarmsegmentresektion durchgeführt. Die enteroenterale Invagination ist im Erwachsenenalter ein sehr seltenes Ereignis, bei der meistens eine Ursache (oft Tumore) als Auslöser der Invagination ermittelt werden kann. Durch Peristaltik und Ingesta wird der nach aboral bewegte Tumor zum Motor der Invagination. Prädilektionsorte sind die Übergänge eines beweglichen zu einem retroperitoneal fixierten Darmabschnitts (z. B. Ileozökalregion). Die Sonographie des Abdomens ist die Methode der ersten Wahl bei der Diagnose einer enteroenteralen Invagination. Beim Erwachsenen ist die operative Beseitigung der Invagination und deren Ursache (meist Tumore) angezeigt.
Entero-enteric invagination of the small intestine in adultsA rare cause of abdominal distress
The present paper reports on a 43-year-old female patient who complained over a number of weeks of paroxysms of crampy pain in the mesogastrium. The diagnosis of ileoileal invagination was only made after she had been admitted to hospital for the third time. The following false diagnoses had been made during the 4-week course of the condition: pyelonephritis, acute appendicitis, chronic appendicitis and, most recently psychosomatic abdominal distress. The patient was initially treated with antibiotics and finally with psychotropic drugs. Eventually ultrasound suggested the diagnosis of invagination of the small intestine, which was then verified by conventional barium follow-through radiography. The patient subsequently underwent resection of a segment of the small intestine. Entero-enteric invagination is a very rare event in adults, in which a single (often malignant) cause is identified as triggering the invagination. Peristalsis and ingested food push the tumor distad, thus acting as a motor for invagination. The preferred localizations are the junctions between freely moving segments to retroperitoneally fixed segments (e.g., ileocecal region). Ultrasound of the abdomen is the examination of choice for diagnosis of enteroenteric invagination. Surgical resection of the invagination and its cause (generally tumors) is indicated in adults.相似文献
48.
Sachs PR 《Journal of healthcare materiel management》1993,11(3):36, 38-36, 43
In the past five years the number of hospitals in financial distress has increased alarmingly. And though hospital administrators are feeling more optimistic now that their institutions will survive, they recognize the need to remain vigilant. It is important to recognize the warning signs of financial distress. Hospitals normally proceed through four stages of financial disintegration if no measures are taken to intercede: weak performance/condition, default, bankruptcy and dissolution. As the stages progress, fewer options for redress can be taken and loss of personnel and assets becomes inevitable. Materiel managers who regularly monitor key statistics, such as non-salary expenses per adjusted occupied bed, days in accounts payable, inventory dollars per adjusted occupied bed and so forth, can recognize the warning signs and take appropriate measures. Corrective actions can include reducing inventory levels, renegotiating contracts and leases, rebidding key contracts and supply items and extending purchase payment terms. A case study shows how a medical center experiencing weak performance implemented expense reductions in utilization, contracts, purchase costs/rebidding and inventory for substantial savings. 相似文献
49.
K. Laborde C. Levy-Marchal C. Kindermans M. Dechaux P. Czernichow C. Sachs 《Pediatric nephrology (Berlin, Germany)》1990,4(1):39-43
Renal function has been evaluated in 45 diabetic children (age 12.5±4 years) with a mean diabetes duration of 4.9±3.5 years. Glomerular filtration rate (GFR; inulin and creatinine clearances), renal plasma flow (RPF; PAH clearance), resting urinary albumin excretion (UAE) were measured and compared with indexes of metabolic control: Hb A1C and blood glucose values (mean, post-prandial and maximal excursion) on the same day. GFR (inulin clearance) and RPF were significantly increased in the diabetic group (171±31 and 778±172 ml/min per 1.73 m2) compared with controls (124±18 and 631±128 ml/min per 1.73 m2). Both parameters were strongly correlated (r=0.73;P<0.001). Creatinine clearance was not correlated to inulin clearance. Hyperfiltration (inulin clearance above 160 ml/min per 1.73 m2) was noted in 61% of the patients and was independent of diabetes duration. Five diabetic children had a UAE level above 15 g/min. No relationship could be established between UAE and any of the metabolic indexes; GFR was weakly correlated to HbA1C (r=0.35;P<0.05), to mean (r=0.35;P<0.05) and post-prandial blood glucose (r=0.37;P<0.05). In contrast, there was a strong correlation between GFR and the maximal blood excursion (r=0.62;P<0.001). The study shows that renal abnormalities can be detected with a high frequency in diabetic subjects characterized by both an early onset and a short duration of diabetes and suggests the need for a more systematic evaluation of renal parameters in this population. 相似文献
50.