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951.
David K. Howard Jeffrey Schlom Paul B. Fisher 《In vitro cellular & developmental biology. Plant》1983,19(1):58-66
Summary We have studied the process of mammary cell transformation in vitro using a single cell clone (Clone 18) from a presumptive
epithelial cell line, C57MG, derived from a normal mammary gland; a mouse mammary tumor virus (MMTV) host-range variant (RIII)vp4;
and the potent initiating carcinogen 7,12-dimethylbenz(a)anthracene (DMBA). After several serial subcultures, cells treated with virus and then with carcinogen exhibited an altered
(transformed) morphology, a dramatic increase in anchorage independence, an increase in multinucleation after exposure to
cytochalasin B, an enhanced ability to proliferate in low Ca2+ (0.01 mM) medium, and tumorigenicity when inoculated subcutaneously into athymic (nude) mice. Although some of these phenotypic alterations
were observed also in cultures treated singly with MMTV or DMBA and in cultures exposed to DMBA before infection with MMTV,
enhanced cytochalasin B multinucleation and tumorigenicity were properties observed only in mass cultures of cloned cells
first infected with MMTV and then exposed to DMBA. This demonstrates for the first time that exposure of presumptive mammary
epithelial cells to MMTV followed by DMBA, but not to either agent alone or to DMBA followed by MMTV, results in malignant
transformation of these cells.
Support for these studies was provided in part by the National Cancer Institute, Bethesda, Md., Contract N01-CP-01018. 相似文献
952.
Paul J. Price Angela E. Auletta Martin P. King Patricia M. Hugunin Robert J. Huebner 《In vitro cellular & developmental biology. Plant》1976,12(8):595-598
Summary Fischer rat embryo cells chronically infected with Rauscher murine leukemia virus, and known to be sensitive to transformation
by potent chemical carcinogens, were transformed by the weak carcinogen 4-nitropyridine-1-oxide. Transformed cells grew in
semi-solid agar and produced tumors in newborn Fischer rats. Transformation was inhibited by antisera specific for the ecotropic
Rauscher murine leukemia virus, but not by antisera of equal toxicity specific for xenotropic Swiss mouse AT-124 virus.
This work was supported by contract NO1-CP-43240 within the Virus Cancer Program of the National Cancer Institute. 相似文献
953.
954.
The Agrobacterium rhizogenes pRi TL-DNA segment as a gene vector system for transformation of plants
Jens Stougaard Dorte Abildsten Kjeld A. Marcker 《Molecular & general genetics : MGG》1987,207(2-3):251-255
Summary A plant gene transfer system was developed from the Agrobacterium rhizogenes pRi15834 TL-DNA region. Intermediate integration vectors constructed from ColE1-derived plasmids served as cloning vectors in Escherichia coli and formed cointegrates into the TL-DNA after transfer to A. rhizogenes. An A. rhizogenes strain with pBR322 plasmid sequences replacing part of the TL-DNA was also constructed. Plasmids unable to replicate in Agrobacterium can integrate into this TL-DNA by homologous recombination through pBR322 sequences. No loss of pathogenicity was observed with the strains formed after integration of intermediate vectors or strains carrying pBR322 in the TL-DNA segment. Up to 15 kb of DNA have been transferred to plant cells with these systems. The T-DNA from a binary vector was cotransformed into hairy roots which developed after transfer of the wild-type pRi T-DNA. Tested on Lotus corniculatus the TL-derived vector system transformed 90% of the developed roots and the T-DNA from the binary vector was cotransformed into 60% of the roots. Minimum copy numbers of one to five were found. Both constitutive and organ-specific plant genes were faithfully expressed after transfer to the legume L. corniculatus. 相似文献
955.
H. Uchimiya H. Hirochika H. Hashimoto A. Hara T. Masuda T. Kasumimoto H. Harada J. -E. Ikeda M. Yoshioka 《Molecular & general genetics : MGG》1986,205(1):1-8
Summary A plasmid containing two marker genes for expression in plants was constructed. This 16 kb vector, pCT1T3, contains an intact
nopaline synthase gene and a chimaeric gene consisting of the promoter and terminator regions from cauliflower mosaic virus
gene VI and a structural gene, aminoglycoside phosphotransferase (APH(3′)II), from the bacterial transposon Tn5. After transformation
of tobacco mesophyll protoplasts with this plasmid, several kanamycin-resistant transformants were obtained. Intensive studies
on the drug tolerance of growth and differentiation of the transformants showed that the chimaeric gene was stably expressed.
Of 17 independent transformants, 3 (about 18%) expressed the two marker genes, regardless of the state of differentiation,
as did individual plants regenerated from the same callus. Multiple copies of the inserted DNA were found in some transformants.
Viable seeds were produced by 12 out of 15 independent transformants. Seeds obtained by self-pollination were germinated on
medium containing kanamycin sulphate. With the exception of one clone, resistant seedlings with green leaves and sensitive
seedlings with white leaves were found to segregate in a 3:1 ratio. This suggests that the inheritance of the inserted gene
is Mendelian. A reciprocal cross between the transformants and wild-type tobacco also showed nuclear transmission of the APH(3′)II
gene. This was consistently maintained in a subclone of the same transformant derived from the same callus line. Stable inheritance
of the single dominant character was also seen among seeds formed in several different flower pods of the same individual
plants.
Two clones were also found to synthesize nopaline in addition to expressing APH(3′)II. Analysis of the progeny obtained by
self-crosses of such transformants revealed the simultaneous expression of these two enzymes, indicating that the two marker
genes are linked on the same chromosome. 相似文献
956.
J. Baumgartner I. E. Ezzat Z. Končeková 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,72(2):264-268
Summary Two experiments were conducted to verify the real possibility for use of the genetic transformation technique as described by Pandey and Patchel in chickens in commercial poultry breeding. Multiple recessive and multiple dominant marker stocks were employed, as well as a tester and a donor line. Recipient tester females were first inseminated with dominant donor semen which was irradiated with doses of 60Co gamma irradiation ranging from 100 to 800 Gy (control group) and 24 h later were reinseminated with unirradiated, normal semen of the recipient strain (experimental group). One genetic transformed chicken was found in the first experiment; no genetic transformed event occurred in the second experiment but one embryo was present in the 600 Gy irradiated group with parthenogenetic development capable of giving a live chick. One hundred Gy was observed not to be enough to destroy completely sperm fertilizing ability. An increased frequency of parthenogenetic development was found in all groups after insemination with irradiated semen. There were 11 individuals with developmental abnormalities from the total of 1264 analysed embryos which died after the 18th day of incubation. We concluded that egg transformation is a rare event in domestic fowl and further research for use of this technique in commercial poultry breeding is needed. 相似文献
957.
I. L. Sun P. Navas F. L. Crane J. Y. Chou H. Löw 《Journal of bioenergetics and biomembranes》1986,18(6):471-485
Transplasma membrane electron transport activity by fetal rat liver cells (RLA209-15) infected with a temperature-sensitive strain of SV40 has been measured with cells grown at the restrictive temperature (40°C) and permissive temperature (33°C). The transformed cells grown at 33°C had only one-half the rate of external ferricyanide reduction as the nontransformed cells held at 40°C. Both theK
m
andV
max for ferricyanide reduction were changed in the transformed state. The change inV
max can be based on a decrease of NADH in the transformed cells. The change in rate with ferricyanide does not depend on change in surface charge. Reduction of external ferricyanide was accompanied by release of protons from the cells. The ratio of protons released to ferricyanide reduced was higher in the transformed cells than in the non-transformed cells. Since the transplasma membrane electron transport has been shown to stimulate cell growth under limiting serum, the changes in the plasma membrane electron transport and proton release in transformed cells may relate to modification of growth control. 相似文献
958.
The cynomolgus monkey was studied as an animal model to investigate the cell-mediated immunity induced by vaccines. Optimal conditions are described to isolate peripheral blood lymphocytes. Lymphocyte transformation tests were performed with tetanus toxoid and smallpox vaccine. Antigen-specific lymphocyte transformations with smallpox vaccine could only be demonstrated when lymphocytes were obtained from vaccinated monkeys. Tetanus toxoid appeared to be a weak antigen. However, after adsorption of the toxoid to aluminum phosphate, a significant antigen-specific lymphocyte transformation was observed. 相似文献
959.
D.B. Adams 《International journal for parasitology》1981,11(4):309-317
Haemonchus contortus infection, which causes a blood loss anaemia in sheep, depleted leukocytes and produced leukopenia and a mild lymphopenia. Thymus atrophy, a decreased size of spleen and enlargement of adrenal glands occurred concomitantly in infected sheep which suggested that they were caused by the stress of infection. The overwhelming change in bone marrow of infected sheep was a 4-fold increase in erythroid series cells.Primary immunization with rat erythrocytes produced similar haemagglutinating antibody responses in infected sheep and in sheep allowed to recover from infection after treatment with thiabendazole. This suggests that extant infection with H. contortus was not associated with a secondary immunodeficiency. Blastogenic responses of blood lymphocytes from infected sheep to larval antigen correlated with faecal egg counts but not with haematocrit or leukocyte values. These results suggest that the unresponsiveness of lymphocytes to worm antigen which occur during infection with H. contortus is more closely related to contact with the parasite than to the pathological effects of infection. 相似文献
960.
George E. Milo Richard G. Olsen Steven E. Weisbrode John A. McCloskey 《In vitro cellular & developmental biology. Plant》1980,16(9):813-822
Summary Human diploid cells morphologically transformed by feline sarcoma virus were serially propagated under selective cell culture
conditions. When injected into nude mice prior to passage in soft agar (0.35%), morphologically transformed cells did not
produce tumors. However, when propagated under selective cell culture conditions, transformed cells grew in soft agar and,
when injected subcutaneously into the subcapsular region of the nμ/nμ mice, produced neoplastic nodules histopathologically
interpreted as fibromas. Karyological examination of cell populations grown out from the tumors confirmed that the tumors
were composed of human cells. Examination of electron micrographs of the excised tumor tissue revealed the presence of budding
virus particles. Tumor cells isolated from nude mice and morphologicaly transformed cells both contained the feline concornativirus-associated
cell membrane antigen. It was concluded that expression of feline oncornavirus-associated cell membrane antigen is associated
with an early stage of feline rerovirus-induced carcinogenesis, namely focus formation. In addition, it was shown that FeLV-FeSV
can induce morphological transformation in human cells in vitro and that there is a requirement for the cells to passage through
soft agar before subsequent tumor formation (neoplastic transformation) can be demonstrated.
This work was supported in part by NIH-NCI RO1-259007, NO1-CP-3571 and CPV08 103563, and Air Force F49620-77-C-110. 相似文献