全文获取类型
收费全文 | 6148篇 |
免费 | 441篇 |
国内免费 | 6篇 |
专业分类
6595篇 |
出版年
2023年 | 44篇 |
2022年 | 110篇 |
2021年 | 181篇 |
2020年 | 103篇 |
2019年 | 116篇 |
2018年 | 183篇 |
2017年 | 134篇 |
2016年 | 222篇 |
2015年 | 307篇 |
2014年 | 322篇 |
2013年 | 437篇 |
2012年 | 520篇 |
2011年 | 526篇 |
2010年 | 311篇 |
2009年 | 287篇 |
2008年 | 368篇 |
2007年 | 411篇 |
2006年 | 348篇 |
2005年 | 326篇 |
2004年 | 269篇 |
2003年 | 258篇 |
2002年 | 238篇 |
2001年 | 48篇 |
2000年 | 28篇 |
1999年 | 39篇 |
1998年 | 47篇 |
1997年 | 55篇 |
1996年 | 28篇 |
1995年 | 36篇 |
1994年 | 31篇 |
1993年 | 34篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 21篇 |
1983年 | 13篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1973年 | 4篇 |
1960年 | 4篇 |
排序方式: 共有6595条查询结果,搜索用时 15 毫秒
41.
Maurizio Meta Marco Ponte Marina Guastella Claudia Semino Gabriella Pietra Giovanni Battista Ratto Giovanni Melioli 《Cancer immunology, immunotherapy : CII》1995,40(4):235-240
Despite the combined use of surgery and chemoradiotherapy, the poor prognosis of advanced non-smallcell lung cancer (NSCLC) requires the definition of new therapeutic approaches. The presence of T lymphocytes, with peculiar phenotypic, functional and molecular characteristics within the tumour, suggested the possible use of these cells, expanded in vitro, in protocols of adoptive immunotherapy. We have described how a population of oligoclonal T lymphocytes, derived from advanced NSCLC, can be expanded in vitro and has the capability of lysing autologous cancer cells. What is more important, we observed that patients with advanced NSCLC, treated with TIL expanded in vitro and recombinant interleukin-2, seemed to have a disease-free period longer than that of patients treated with conventional chemoradiotherapy. in an attempt to find new sources of specific lymphocytes for immunotherapy, we describe the analysis of the phenotypic, functional and molecular characteristics of T lymphocytes, derived from lymph nodes draining advanced NSCLC. In this paper we show that these cells, have restriction patterns of T cell receptor chain similar to those detectable in the population of infiltrating T lymphocytes. This finding suggests that T cells derived from draining lymph nodes of advanced NSCLC have peculiar characteristics and can be a suitable source of effector cells for protocols of adoptive immunotherapy in lung cancer treatment. 相似文献
42.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,804(2):145-153
The true level of hexokinase in rabbit erythrocytes was determined by three different methods, including the spectrophotometric glucose-6-phosphate dehydrogenase coupled assay and a new radioisotopic assay. The value found at 37°C (pH 7.2) was 10.23±1.90 μmol/h per ml red blood cells, which is lower than previously reported values. More than 40 cellular components of the rabbit erythrocytes were tested for their effects on the enzyme. Their intracellular concentrations were also determined. Several of these compounds were found to be competitive inhibitors of the enzyme with respect to Mg·ATP2?. Furthermore, reduced glutathione at a concentration of 1 mM was able to maintain hexokinase in the reduced state with full catalytic activity. The ability of orthophosphate to remove the inhibition of some phosphorylated compounds was examined under conditions similar to cellular (pH 7.2 and 50 μM of orthophosphate) and found to be of no practical interest. In contrast, the binding of ATP4? and 2,3-diphosphoglycerate to the rabbit hemoglobin significantly modifies their intracellular concentrations and the formation of the respective Mg complexes. The pH-dependence of the reaction velocity and of the kinetic properties of the enzyme in different buffer systems were also considered. This information was computerized, and the rate of glucose phosphorylation in the presence of the mentioned compounds was determined. The value obtained, 1.94±0.02 μmol/h per ml red blood cells, is practically identical to the measured rate of glucose utilization by intact rabbit erythrocytes (1.92±0.3 μmol/h per ml red blood cells). These results provide further evidence for the central role of hexokinase in the regulation of red blood cell glycolysis. 相似文献
43.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Molecular and cellular biochemistry》1984,61(1):83-92
Summary Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in reticulocytes as two distinct molecular forms, designated hexokinase Ia and Ib, but only one of these was consistently present in mature red cells. In vivo, hexokinase la and Ib show a decay rate of 3 and 8% a day, respectively, while in vitro they show a similar stability.The possibility that the proteolytic activities of the reticulocyte could be responsible for the fast decay of hexokinase was investigated. No differences were found in the decay rates of hexokinase la and Ib during in vitro reticulocyte maturation in presence or absence of proteolytic inhibitors. Contrariwise, many findings indicate the ATP-dependent proteolytic system of the reticulocyte as a possible mechanism. In fact, the decay of hexokinase and the degradation of 3H-globins are both stimulated by ATP and ubiquitin; they show similar kinetic properties and both disappear during reticulocyte maturation.The cellular localization of hexokinase la and Ib was shown to be responsible for the differences found between their decay rates.Abbreviations PMSF
phenylmethylsulfonyl fluoride
- TPCK
1-1-tosylamide-2-phenylethyl-chloromethyl ketone
- TLCK
N -p-tosyl-L-lysine chloromethyl ketone 相似文献
44.
45.
Summary Three patients with mental retardation and multiple congenital abnormalities are described.Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype. 相似文献
46.
Walter Borzani Haroldo Hiss Teresinha W. de Santos Marina L. R. Vairo 《Biotechnology letters》1992,14(10):981-984
Summary A mathematical model is proposed to explain the influence of the volume fraction of inoculum on the fermentation time and ethanol productivity in semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast.Nomenclature a, b, c, d
constants, see equation (5)
- Eo
initial ethanol concentration
- Ef
final ethanol concentration
- K1, K2, K3
constants, see equation (1)
- P
ethanol productivity
- Pc
calculated values of P
- Pe
experimental values of P
- r
correlation coefficient
- So
initial TRS concentration
- Sm
TRS concentration of the feeding mash
- T
fermentation time (average of the experimental values)
- Tc
calculated value of T
- Te
experimental value of T
- TRS
total reducing sugars calculated as glucose
- Uo
initial urea concentration
- Um
urea concentration of the feeding mash
- V
reactor working volume
- Vi
volume of the inoculum
-
volume fraction of inoculum=Vi/V 相似文献
47.
48.
Marina Bandeira Marc-André Bouchard Luc Granger 《Applied psychophysiology and biofeedback》1982,7(3):317-330
This paper discusses the general methodological controversy between individual and group research approaches by comparing the main characteristics of these two methods as applied to the specific context of basic research on voluntary heart rate control. A review of the literature published over the past 19 years in this area of study shows an imbalance in the frequency of utilization of these two methods that strongly favors short-term group designs. Implications of this research tendency are discussed. The relevance and the advantages of applying the individual approach to voluntary autonomic control research are outlined. This area is particularly amenable to the individual approach because the phenomena under study seem to be characterized by, among other things, a smaller intrasubject than intersubject variability. It is suggested that the present imbalanced tendency in the choice of a research method be corrected and that researchers adopt a more flexible attitude in the choice of the best method for studying each specific problem. 相似文献
49.
Summary We describe a reciprocal translocation (10;13) in a man, ascertained through the study of meiosis in semen, and a partial trisomy 10q in his abnormal son. The phenotypic anomalies of the partial 10q trisomy syndrome are probably due to the presence in triplicate of the region q25qter of chromosome 10. 相似文献
50.
Nitrate, ammonia, urea, and glycine were compared as nitrogen sources for Acetabularia mediterranea. Cells grew normally in media containing nitrate or urea, while cells did not grow at all when the same amount of N was supplied as ammonium ion. The utilization of glycine remains questionable. Cells in medium without added N (NDM) increased in length and some formed reproductive caps. The whorls of vegetative cells showed considerable hypertrophy in NDM and in glycine. This hypertrophy was due to the elongation of only the first-(a1) and second- (a2) order articles. When cut, the basal portion of cells without added N regenerated new apices with whorls. The development of these whorls was inversely proportional to the NO2 concentration. Analyses showed that the intracellular nitrogen pool in young cells and regenerating bases was very small, about 1/10 of that of fully grown cells. Therefore we suggest that trace amounts of N contaminants in the medium supported growth and development, the uptake of which was facilitated by the hypertrophied whorls, under N-limited conditions. 相似文献